chore: use fstrings

.flake8

@@ -2,6 +2,8 @@
 min_python_version = 3.6.0
 max-line-length = 88
 ban-relative-imports = true
+# flake8-use-fstring: https://github.com/MichaelKim0407/flake8-use-fstring#--percent-greedy-and---format-greedy
+format-greedy = 1
 inline-quotes = double
 # Allow omission of a return type hint for __init__ if at least one argument is annotated
 # used by flake8-annotations

.pre-commit-config.yaml

@@ -42,6 +42,7 @@ repos:
           - flake8-tidy-imports==4.5.0
           - flake8-type-checking==1.1.0
           - flake8-typing-imports==1.11.0
+          - flake8-use-fstring==1.3
           - pep8-naming==0.12.1
 
   - repo: https://github.com/asottile/pyupgrade

src/poetry/config/config.py

@@ -111,9 +111,7 @@ class Config:
         # Looking in the environment if the setting
         # is set via a POETRY_* environment variable
         if self._use_environment:
-            env = "POETRY_{}".format(
-                "_".join(k.upper().replace("-", "_") for k in keys)
-            )
+            env = "POETRY_" + "_".join(k.upper().replace("-", "_") for k in keys)
             env_value = os.getenv(env)
             if env_value is not None:
                 return self.process(self._get_normalizer(setting_name)(env_value))

src/poetry/console/application.py

@@ -39,13 +39,9 @@ if TYPE_CHECKING:
 
 def load_command(name: str) -> Callable:
     def _load() -> Type[Command]:
-        module = import_module(
-            "poetry.console.commands.{}".format(".".join(name.split(" ")))
-        )
-        command_class = getattr(
-            module, "{}Command".format("".join(c.title() for c in name.split(" ")))
-        )
-
+        words = name.split(" ")
+        module = import_module("poetry.console.commands." + ".".join(words))
+        command_class = getattr(module, "".join(c.title() for c in words) + "Command")
         return command_class()
 
     return _load

src/poetry/console/commands/build.py

@@ -27,9 +27,7 @@ class BuildCommand(EnvCommand):
 
         package = self.poetry.package
         self.line(
-            "Building <c1>{}</c1> (<c2>{}</c2>)".format(
-                package.pretty_name, package.version
-            )
+            f"Building <c1>{package.pretty_name}</c1> (<c2>{package.version}</c2>)"
         )
 
         builder = Builder(self.poetry)

src/poetry/console/commands/cache/clear.py

@@ -43,7 +43,7 @@ class CacheClearCommand(Command):
             if not self.option("all"):
                 raise RuntimeError(
                     "Add the --all option if you want to clear all "
-                    "{} caches".format(parts[0])
+                    f"{parts[0]} caches"
                 )
 
             if not os.path.exists(str(cache_dir)):

src/poetry/console/commands/config.py

@@ -230,7 +230,7 @@ To remove a repository (repo is a short alias for repositories):
                 elif len(values) != 2:
                     raise ValueError(
                         "Expected one or two arguments "
-                        "(username, password), got {}".format(len(values))
+                        f"(username, password), got {len(values)}"
                     )
                 else:
                     username = values[0]
@@ -270,7 +270,7 @@ To remove a repository (repo is a short alias for repositories):
 
             return 0
 
-        raise ValueError("Setting {} does not exist".format(self.argument("key")))
+        raise ValueError(f"Setting {self.argument('key')} does not exist")
 
     def _handle_single_value(
         self,
@@ -307,19 +307,16 @@ To remove a repository (repo is a short alias for repositories):
 
                 continue
             elif isinstance(value, list):
-                value = [
+                value = ", ".join(
                     json.dumps(val) if isinstance(val, list) else val for val in value
-                ]
-
-                value = "[{}]".format(", ".join(value))
+                )
+                value = f"[{value}]"
 
             if k.startswith("repositories."):
-                message = "<c1>{}</c1> = <c2>{}</c2>".format(
-                    k + key, json.dumps(raw_val)
-                )
+                message = f"<c1>{k + key}</c1> = <c2>{json.dumps(raw_val)}</c2>"
             elif isinstance(raw_val, str) and raw_val != value:
-                message = "<c1>{}</c1> = <c2>{}</c2>  # {}".format(
-                    k + key, json.dumps(raw_val), value
+                message = (
+                    f"<c1>{k + key}</c1> = <c2>{json.dumps(raw_val)}</c2>  # {value}"
                 )
             else:
                 message = f"<c1>{k + key}</c1> = <c2>{json.dumps(value)}</c2>"
@@ -361,12 +358,11 @@ To remove a repository (repo is a short alias for repositories):
                     continue
 
                 if isinstance(value, list):
-                    value = [
+                    value = ", ".join(
                         json.dumps(val) if isinstance(val, list) else val
                         for val in value
-                    ]
-
-                    value = "[{}]".format(", ".join(value))
+                    )
+                    value = f"[{value}]"
 
                 value = json.dumps(value)
 

src/poetry/console/commands/debug/info.py

@@ -17,9 +17,7 @@ class DebugInfoCommand(Command):
             "\n".join(
                 [
                     f"<info>Version</info>: <comment>{self.poetry.VERSION}</>",
-                    "<info>Python</info>:  <comment>{}</>".format(
-                        poetry_python_version
-                    ),
+                    f"<info>Python</info>:  <comment>{poetry_python_version}</>",
                 ]
             )
         )

src/poetry/console/commands/env/info.py

@@ -52,15 +52,14 @@ class EnvInfoCommand(Command):
         self.line("")
 
         system_env = env.parent_env
+        python = ".".join(str(v) for v in system_env.version_info[:3])
         self.line("<b>System</b>")
         self.line(
             "\n".join(
                 [
                     f"<info>Platform</info>:   <comment>{env.platform}</>",
                     f"<info>OS</info>:         <comment>{env.os}</>",
-                    "<info>Python</info>:     <comment>{}</>".format(
-                        ".".join(str(v) for v in system_env.version_info[:3])
-                    ),
+                    f"<info>Python</info>:     <comment>{python}</>",
                     f"<info>Path</info>:       <comment>{system_env.path}</>",
                     f"<info>Executable</info>: <comment>{system_env.python}</>",
                 ]

src/poetry/console/commands/init.py

@@ -146,13 +146,11 @@ The <c1>init</c1> command creates a basic <comment>pyproject.toml</> file in the
         python = self.option("python")
         if not python:
             current_env = SystemEnv(Path(sys.executable))
-            default_python = "^{}".format(
-                ".".join(str(v) for v in current_env.version_info[:2])
+            default_python = "^" + ".".join(
+                str(v) for v in current_env.version_info[:2]
             )
             question = self.create_question(
-                "Compatible Python versions [<comment>{}</comment>]: ".format(
-                    default_python
-                ),
+                f"Compatible Python versions [<comment>{default_python}</comment>]: ",
                 default=default_python,
             )
             python = self.ask(question)
@@ -282,9 +280,7 @@ The <c1>init</c1> command creates a basic <comment>pyproject.toml</> file in the
                         choices.append(found_package.pretty_name)
 
                     self.line(
-                        "Found <info>{}</info> packages matching <c1>{}</c1>".format(
-                            len(matches), package
-                        )
+                        f"Found <info>{len(matches)}</info> packages matching <c1>{package}</c1>"
                     )
 
                     package = self.choice(
@@ -314,9 +310,7 @@ The <c1>init</c1> command creates a basic <comment>pyproject.toml</> file in the
                         )
 
                         self.line(
-                            "Using version <b>{}</b> for <c1>{}</c1>".format(
-                                package_constraint, package
-                            )
+                            f"Using version <b>{package_constraint}</b> for <c1>{package}</c1>"
                         )
 
                     constraint["version"] = package_constraint

src/poetry/console/commands/install.py

@@ -176,19 +176,15 @@ dependencies and not including the current project, run the command with the
             # If this is a true error it will be picked up later by build anyway.
             return 0
 
+        log_install = (
+            f"<b>Installing</> the current project: <c1>{self.poetry.package.pretty_name}</c1> "
+            f"(<{{tag}}>{self.poetry.package.pretty_version}</>)"
+        )
+        overwrite = self._io.output.is_decorated() and not self.io.is_debug()
         self.line("")
-        if not self._io.output.is_decorated() or self.io.is_debug():
-            self.line(
-                "<b>Installing</> the current project: <c1>{}</c1> (<c2>{}</c2>)".format(
-                    self.poetry.package.pretty_name, self.poetry.package.pretty_version
-                )
-            )
-        else:
-            self.write(
-                "<b>Installing</> the current project: <c1>{}</c1> (<c2>{}</c2>)".format(
-                    self.poetry.package.pretty_name, self.poetry.package.pretty_version
-                )
-            )
+        self.write(log_install.format(tag="c2"))
+        if not overwrite:
+            self.line("")
 
         if self.option("dry-run"):
             self.line("")
@@ -196,12 +192,8 @@ dependencies and not including the current project, run the command with the
 
         builder.build()
 
-        if self._io.output.is_decorated() and not self.io.is_debug():
-            self.overwrite(
-                "<b>Installing</> the current project: <c1>{}</c1> (<success>{}</success>)".format(
-                    self.poetry.package.pretty_name, self.poetry.package.pretty_version
-                )
-            )
+        if overwrite:
+            self.overwrite(log_install.format(tag="success"))
             self.line("")
 
         return 0

src/poetry/console/commands/new.py

@@ -50,7 +50,7 @@ class NewCommand(Command):
         if path.exists() and list(path.glob("*")):
             # Directory is not empty. Aborting.
             raise RuntimeError(
-                "Destination <fg=yellow>{}</> " "exists and is not empty".format(path)
+                f"Destination <fg=yellow>{path}</> " "exists and is not empty"
             )
 
         readme_format = self.option("readme") or "md"
@@ -64,9 +64,7 @@ class NewCommand(Command):
                 author += f" <{author_email}>"
 
         current_env = SystemEnv(Path(sys.executable))
-        default_python = "^{}".format(
-            ".".join(str(v) for v in current_env.version_info[:2])
-        )
+        default_python = "^" + ".".join(str(v) for v in current_env.version_info[:2])
 
         layout_ = layout_(
             name,
@@ -83,7 +81,5 @@ class NewCommand(Command):
             path = path.relative_to(Path.cwd())
 
         self.line(
-            "Created package <info>{}</> in <fg=blue>{}</>".format(
-                layout_._package_name, path.as_posix()
-            )
+            f"Created package <info>{layout_._package_name}</> in <fg=blue>{path.as_posix()}</>"
         )

src/poetry/console/commands/plugin/show.py

@@ -24,6 +24,7 @@ class PluginShowCommand(Command):
         from poetry.repositories.installed_repository import InstalledRepository
         from poetry.utils.env import EnvManager
         from poetry.utils.helpers import canonicalize_name
+        from poetry.utils.helpers import pluralize
 
         plugins: DefaultDict[str, Dict[str, Union["Package", List[str]]]] = defaultdict(
             lambda: {
@@ -57,27 +58,21 @@ class PluginShowCommand(Command):
 
         for name, info in plugins.items():
             package = info["package"]
+            description = " " + package.description if package.description else ""
             self.line("")
-            self.line(
-                "  • <c1>{}</c1> (<c2>{}</c2>){}".format(
-                    name,
-                    package.version,
-                    " " + package.description if package.description else "",
-                )
-            )
+            self.line(f"  • <c1>{name}</c1> (<c2>{package.version}</c2>){description}")
             provide_line = "     "
             if info["plugins"]:
-                provide_line += " <info>{}</info> plugin{}".format(
-                    len(info["plugins"]), "s" if len(info["plugins"]) > 1 else ""
-                )
+                count = len(info["plugins"])
+                provide_line += f" <info>{count}</info> plugin{pluralize(count)}"
 
             if info["application_plugins"]:
                 if info["plugins"]:
                     provide_line += " and"
 
-                provide_line += " <info>{}</info> application plugin{}".format(
-                    len(info["application_plugins"]),
-                    "s" if len(info["application_plugins"]) > 1 else "",
+                count = len(info["application_plugins"])
+                provide_line += (
+                    f" <info>{count}</info> application plugin{pluralize(count)}"
                 )
 
             self.line(provide_line)
@@ -87,9 +82,7 @@ class PluginShowCommand(Command):
                 self.line("      <info>Dependencies</info>")
                 for dependency in package.requires:
                     self.line(
-                        "        - {} (<c2>{}</c2>)".format(
-                            dependency.pretty_name, dependency.pretty_constraint
-                        )
+                        f"        - {dependency.pretty_name} (<c2>{dependency.pretty_constraint}</c2>)"
                     )
 
         return 0

src/poetry/console/commands/publish.py

@@ -49,8 +49,8 @@ the config command.
         # Building package first, if told
         if self.option("build"):
             if publisher.files and not self.confirm(
-                "There are <info>{}</info> files ready for publishing. "
-                "Build anyway?".format(len(publisher.files))
+                f"There are <info>{len(publisher.files)}</info> files ready for publishing. "
+                "Build anyway?"
             ):
                 self.line_error("<error>Aborted!</error>")
 

src/poetry/console/commands/remove.py

@@ -88,9 +88,7 @@ list of installed packages
         not_found = set(packages).difference(removed)
         if not_found:
             raise ValueError(
-                "The following packages were not found: {}".format(
-                    ", ".join(sorted(not_found))
-                )
+                "The following packages were not found: " + ", ".join(sorted(not_found))
             )
 
         # Refresh the locker

src/poetry/console/commands/run.py

@@ -54,8 +54,8 @@ class RunCommand(EnvCommand):
         cmd += [
             "import sys; "
             "from importlib import import_module; "
-            "sys.argv = {!r}; {}"
-            "import_module('{}').{}()".format(args, src_in_sys_path, module, callable_)
+            f"sys.argv = {args!r}; {src_in_sys_path}"
+            f"import_module('{module}').{callable_}()"
         ]
 
         return self.env.execute(*cmd)

src/poetry/console/commands/self/update.py

@@ -139,9 +139,7 @@ class SelfUpdateCommand(Command):
 
         self.line("")
         self.line(
-            "<c1>Poetry</c1> (<c2>{}</c2>) is installed now. Great!".format(
-                release.version
-            )
+            f"<c1>Poetry</c1> (<c2>{release.version}</c2>) is installed now. Great!"
         )
 
         return 0

src/poetry/console/commands/shell.py

@@ -25,8 +25,7 @@ If one doesn't exist yet, it will be created.
         ) == str(self.env.path)
         if venv_activated:
             self.line(
-                "Virtual environment already activated: "
-                "<info>{}</>".format(self.env.path)
+                f"Virtual environment already activated: <info>{self.env.path}</>"
             )
 
             return

src/poetry/console/commands/show.py

@@ -201,9 +201,7 @@ lists all packages available."""
                 self.line("<info>dependencies</info>")
                 for dependency in pkg.requires:
                     self.line(
-                        " - <c1>{}</c1> <b>{}</b>".format(
-                            dependency.pretty_name, dependency.pretty_constraint
-                        )
+                        f" - <c1>{dependency.pretty_name}</c1> <b>{dependency.pretty_constraint}</b>"
                     )
 
             if required_by:
@@ -303,16 +301,12 @@ lists all packages available."""
             ):
                 continue
 
-            line = "<fg={}>{:{}}{}</>".format(
-                color, name, name_length - len(install_marker), install_marker
-            )
+            line = f"<fg={color}>{name:{name_length - len(install_marker)}}{install_marker}</>"
             if write_version:
-                line += " <b>{:{}}</b>".format(
-                    get_package_version_display_string(
-                        locked, root=self.poetry.file.parent
-                    ),
-                    version_length,
+                version = get_package_version_display_string(
+                    locked, root=self.poetry.file.parent
                 )
+                line += f" <b>{version:{version_length}}</b>"
             if show_latest:
                 latest = latest_packages[locked.pretty_name]
                 update_status = latest_statuses[locked.pretty_name]
@@ -324,13 +318,10 @@ lists all packages available."""
                     elif update_status == "update-possible":
                         color = "yellow"
 
-                    line += " <fg={}>{:{}}</>".format(
-                        color,
-                        get_package_version_display_string(
-                            latest, root=self.poetry.file.parent
-                        ),
-                        latest_length,
+                    version = get_package_version_display_string(
+                        latest, root=self.poetry.file.parent
                     )
+                    line += f" <fg={color}>{version:{latest_length}}</>"
 
             if write_description:
                 description = locked.description
@@ -366,12 +357,7 @@ lists all packages available."""
 
             level = 1
             color = self.colors[level]
-            info = "{tree_bar}── <{color}>{name}</{color}> {constraint}".format(
-                tree_bar=tree_bar,
-                color=color,
-                name=dependency.name,
-                constraint=dependency.pretty_constraint,
-            )
+            info = f"{tree_bar}── <{color}>{dependency.name}</{color}> {dependency.pretty_constraint}"
             self._write_tree_line(io, info)
 
             tree_bar = tree_bar.replace("└", " ")
@@ -414,13 +400,7 @@ lists all packages available."""
             if dependency.name in current_tree:
                 circular_warn = "(circular dependency aborted here)"
 
-            info = "{tree_bar}── <{color}>{name}</{color}> {constraint} {warn}".format(
-                tree_bar=tree_bar,
-                color=color,
-                name=dependency.name,
-                constraint=dependency.pretty_constraint,
-                warn=circular_warn,
-            )
+            info = f"{tree_bar}── <{color}>{dependency.name}</{color}> {dependency.pretty_constraint} {circular_warn}"
             self._write_tree_line(io, info)
 
             tree_bar = tree_bar.replace("└", " ")

src/poetry/console/commands/version.py

@@ -58,9 +58,7 @@ patch, minor, major, prepatch, preminor, premajor, prerelease.
                 self.line(version.to_string())
             else:
                 self.line(
-                    "Bumping version from <b>{}</> to <fg=green>{}</>".format(
-                        self.poetry.package.pretty_version, version
-                    )
+                    f"Bumping version from <b>{self.poetry.package.pretty_version}</> to <fg=green>{version}</>"
                 )
 
             content = self.poetry.file.read()

src/poetry/factory.py

@@ -100,9 +100,7 @@ class Factory(BaseFactory):
         if config_file.exists():
             if io.is_debug():
                 io.write_line(
-                    "<debug>Loading configuration file {}</debug>".format(
-                        config_file.path
-                    )
+                    f"<debug>Loading configuration file {config_file.path}</debug>"
                 )
 
             config.merge(config_file.read())
@@ -114,9 +112,7 @@ class Factory(BaseFactory):
         if auth_config_file.exists():
             if io.is_debug():
                 io.write_line(
-                    "<debug>Loading configuration file {}</debug>".format(
-                        auth_config_file.path
-                    )
+                    f"<debug>Loading configuration file {auth_config_file.path}</debug>"
                 )
 
             config.merge(auth_config_file.read())
@@ -134,9 +130,7 @@ class Factory(BaseFactory):
             is_default = source.get("default", False)
             is_secondary = source.get("secondary", False)
             if io.is_debug():
-                message = "Adding repository {} ({})".format(
-                    repository.name, repository.url
-                )
+                message = f"Adding repository {repository.name} ({repository.url})"
                 if is_default:
                     message += " and setting it as the default one"
                 elif is_secondary:

src/poetry/inspection/info.py

@@ -49,7 +49,7 @@ class PackageInfoError(ValueError):
     def __init__(
         self, path: Union[Path, str], *reasons: Union[BaseException, str]
     ) -> None:
-        reasons = (f"Unable to determine package info for path: {str(path)}",) + reasons
+        reasons = (f"Unable to determine package info for path: {path!s}",) + reasons
         super().__init__("\n\n".join(str(msg).strip() for msg in reasons if msg))
 
 
@@ -178,8 +178,8 @@ class PackageInfo:
             except ValueError:
                 # Likely unable to parse constraint so we skip it
                 self._log(
-                    "Invalid constraint ({}) found in {}-{} dependencies, "
-                    "skipping".format(req, package.name, package.version),
+                    f"Invalid constraint ({req}) found in {package.name}-{package.version} dependencies, "
+                    "skipping",
                     level="warning",
                 )
                 continue
@@ -460,6 +460,10 @@ class PackageInfo:
             dest_dir = venv.path.parent / "dist"
             dest_dir.mkdir()
 
+            pep517_meta_build_script = PEP517_META_BUILD.format(
+                source=path.as_posix(), dest=dest_dir.as_posix()
+            )
+
             try:
                 venv.run_pip(
                     "install",
@@ -470,9 +474,7 @@ class PackageInfo:
                 venv.run(
                     "python",
                     "-",
-                    input_=PEP517_META_BUILD.format(
-                        source=path.as_posix(), dest=dest_dir.as_posix()
-                    ),
+                    input_=pep517_meta_build_script,
                 )
                 return cls.from_metadata(dest_dir)
             except EnvCommandError as e:

src/poetry/installation/chooser.py

@@ -149,8 +149,8 @@ class Chooser:
             wheel = Wheel(link.filename)
             if not wheel.is_supported_by_environment(self._env):
                 raise RuntimeError(
-                    "{} is not a supported wheel for this platform. It "
-                    "can't be sorted.".format(wheel.filename)
+                    f"{wheel.filename} is not a supported wheel for this platform. It "
+                    "can't be sorted."
                 )
 
             # TODO: Binary preference

src/poetry/installation/executor.py

@@ -26,6 +26,7 @@ from poetry.installation.chooser import Chooser
 from poetry.utils._compat import decode
 from poetry.utils.authenticator import Authenticator
 from poetry.utils.env import EnvCommandError
+from poetry.utils.helpers import pluralize
 from poetry.utils.helpers import safe_rmtree
 from poetry.utils.pip import pip_editable_install
 from poetry.utils.pip import pip_install
@@ -221,6 +222,7 @@ class Executor:
 
     def _execute_operation(self, operation: "OperationTypes") -> None:
         try:
+            op_message = self.get_operation_message(operation)
             if self.supports_fancy_output():
                 if id(operation) not in self._sections and self._should_write_operation(
                     operation
@@ -228,27 +230,20 @@ class Executor:
                     with self._lock:
                         self._sections[id(operation)] = self._io.section()
                         self._sections[id(operation)].write_line(
-                            "  <fg=blue;options=bold>•</> {message}: <fg=blue>Pending...</>".format(
-                                message=self.get_operation_message(operation),
-                            ),
+                            f"  <fg=blue;options=bold>•</> {op_message}: <fg=blue>Pending...</>"
                         )
             else:
                 if self._should_write_operation(operation):
                     if not operation.skipped:
                         self._io.write_line(
-                            "  <fg=blue;options=bold>•</> {message}".format(
-                                message=self.get_operation_message(operation),
-                            ),
+                            f"  <fg=blue;options=bold>•</> {op_message}"
                         )
                     else:
                         self._io.write_line(
-                            "  <fg=default;options=bold,dark>•</> {message}: "
+                            f"  <fg=default;options=bold,dark>•</> {op_message}: "
                             "<fg=default;options=bold,dark>Skipped</> "
                             "<fg=default;options=dark>for the following reason:</> "
-                            "<fg=default;options=bold,dark>{reason}</>".format(
-                                message=self.get_operation_message(operation),
-                                reason=operation.skip_reason,
-                            )
+                            f"<fg=default;options=bold,dark>{operation.skip_reason}</>"
                         )
 
             try:
@@ -271,11 +266,7 @@ class Executor:
                 if not self.supports_fancy_output():
                     io = self._io
                 else:
-                    message = (
-                        "  <error>•</error> {message}: <error>Failed</error>".format(
-                            message=self.get_operation_message(operation, error=True),
-                        )
-                    )
+                    message = f"  <error>•</error> {self.get_operation_message(operation, error=True)}: <error>Failed</error>"
                     self._write(operation, message)
                     io = self._sections.get(id(operation), self._io)
 
@@ -288,9 +279,7 @@ class Executor:
                     self._shutdown = True
         except KeyboardInterrupt:
             try:
-                message = "  <warning>•</warning> {message}: <warning>Cancelled</warning>".format(
-                    message=self.get_operation_message(operation, warning=True),
-                )
+                message = f"  <warning>•</warning> {self.get_operation_message(operation, warning=True)}: <warning>Cancelled</warning>"
                 if not self.supports_fancy_output():
                     self._io.write_line(message)
                 else:
@@ -307,13 +296,10 @@ class Executor:
             if self.supports_fancy_output():
                 self._write(
                     operation,
-                    "  <fg=default;options=bold,dark>•</> {message}: "
+                    f"  <fg=default;options=bold,dark>•</> {operation_message}: "
                     "<fg=default;options=bold,dark>Skipped</> "
                     "<fg=default;options=dark>for the following reason:</> "
-                    "<fg=default;options=bold,dark>{reason}</>".format(
-                        message=operation_message,
-                        reason=operation.skip_reason,
-                    ),
+                    f"<fg=default;options=bold,dark>{operation.skip_reason}</>",
                 )
 
             self._skipped[operation.job_type] += 1
@@ -321,11 +307,7 @@ class Executor:
             return 0
 
         if not self._enabled or self._dry_run:
-            self._io.write_line(
-                "  <fg=blue;options=bold>•</> {message}".format(
-                    message=operation_message,
-                )
-            )
+            self._io.write_line(f"  <fg=blue;options=bold>•</> {operation_message}")
 
             return 0
 
@@ -334,9 +316,8 @@ class Executor:
         if result != 0:
             return result
 
-        message = "  <fg=green;options=bold>•</> {message}".format(
-            message=self.get_operation_message(operation, done=True),
-        )
+        operation_message = self.get_operation_message(operation, done=True)
+        message = f"  <fg=green;options=bold>•</> {operation_message}"
         self._write(operation, message)
 
         self._increment_operations_count(operation, True)
@@ -394,38 +375,23 @@ class Executor:
             package_color += "_dark"
 
         if operation.job_type == "install":
-            return "<{}>Installing <{}>{}</{}> (<{}>{}</>)</>".format(
-                base_tag,
-                package_color,
-                operation.package.name,
-                package_color,
-                operation_color,
-                operation.package.full_pretty_version,
+            return (
+                f"<{base_tag}>Installing <{package_color}>{operation.package.name}</{package_color}> "
+                f"(<{operation_color}>{operation.package.full_pretty_version}</>)</>"
             )
 
         if operation.job_type == "uninstall":
-            return "<{}>Removing <{}>{}</{}> (<{}>{}</>)</>".format(
-                base_tag,
-                package_color,
-                operation.package.name,
-                package_color,
-                operation_color,
-                operation.package.full_pretty_version,
+            return (
+                f"<{base_tag}>Removing <{package_color}>{operation.package.name}</{package_color}> "
+                f"(<{operation_color}>{operation.package.full_pretty_version}</>)</>"
             )
 
         if operation.job_type == "update":
-            return "<{}>Updating <{}>{}</{}> (<{}>{}</{}> -> <{}>{}</>)</>".format(
-                base_tag,
-                package_color,
-                operation.initial_package.name,
-                package_color,
-                source_operation_color,
-                operation.initial_package.full_pretty_version,
-                source_operation_color,
-                operation_color,
-                operation.target_package.full_pretty_version,
+            return (
+                f"<{base_tag}>Updating <{package_color}>{operation.initial_package.name}</{package_color}> "
+                f"(<{source_operation_color}>{operation.initial_package.full_pretty_version}</{source_operation_color}> "
+                f"-> <{operation_color}>{operation.target_package.full_pretty_version}</>)</>"
             )
-
         return ""
 
     def _display_summary(self, operations: List["OperationTypes"]) -> None:
@@ -452,21 +418,13 @@ class Executor:
             return
 
         self._io.write_line("")
-        self._io.write_line(
-            "<b>Package operations</b>: "
-            "<info>{}</> install{}, "
-            "<info>{}</> update{}, "
-            "<info>{}</> removal{}"
-            "{}".format(
-                installs,
-                "" if installs == 1 else "s",
-                updates,
-                "" if updates == 1 else "s",
-                uninstalls,
-                "" if uninstalls == 1 else "s",
-                f", <info>{skipped}</> skipped" if skipped and self._verbose else "",
-            )
-        )
+        self._io.write("<b>Package operations</b>: ")
+        self._io.write(f"<info>{installs}</> install{pluralize(installs)}, ")
+        self._io.write(f"<info>{updates}</> update{pluralize(updates)}, ")
+        self._io.write(f"<info>{uninstalls}</> removal{pluralize(uninstalls)}")
+        if skipped and self._verbose:
+            self._io.write(f", <info>{skipped}</> skipped")
+        self._io.write_line("")
         self._io.write_line("")
 
     def _execute_install(self, operation: Union["Install", "Update"]) -> int:
@@ -484,11 +442,8 @@ class Executor:
         return status_code
 
     def _execute_uninstall(self, operation: "Uninstall") -> int:
-        message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Removing...</info>".format(
-                message=self.get_operation_message(operation),
-            )
-        )
+        op_msg = self.get_operation_message(operation)
+        message = f"  <fg=blue;options=bold>•</> {op_msg}: <info>Removing...</info>"
         self._write(operation, message)
 
         return self._remove(operation)
@@ -509,11 +464,7 @@ class Executor:
             archive = self._download(operation)
 
         operation_message = self.get_operation_message(operation)
-        message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Installing...</info>".format(
-                message=operation_message,
-            )
-        )
+        message = f"  <fg=blue;options=bold>•</> {operation_message}: <info>Installing...</info>"
         self._write(operation, message)
         return self.pip_install(archive, upgrade=operation.job_type == "update")
 
@@ -539,12 +490,9 @@ class Executor:
 
     def _prepare_file(self, operation: Union["Install", "Update"]) -> Path:
         package = operation.package
+        operation_message = self.get_operation_message(operation)
 
-        message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Preparing...</info>".format(
-                message=self.get_operation_message(operation),
-            )
-        )
+        message = f"  <fg=blue;options=bold>•</> {operation_message}: <info>Preparing...</info>"
         self._write(operation, message)
 
         archive = Path(package.source_url)
@@ -561,11 +509,7 @@ class Executor:
         package = operation.package
         operation_message = self.get_operation_message(operation)
 
-        message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Building...</info>".format(
-                message=operation_message,
-            )
-        )
+        message = f"  <fg=blue;options=bold>•</> {operation_message}: <info>Building...</info>"
         self._write(operation, message)
 
         if package.root_dir:
@@ -622,9 +566,7 @@ class Executor:
         operation_message = self.get_operation_message(operation)
 
         message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Cloning...</info>".format(
-                message=operation_message,
-            )
+            f"  <fg=blue;options=bold>•</> {operation_message}: <info>Cloning...</info>"
         )
         self._write(operation, message)
 
@@ -716,9 +658,7 @@ class Executor:
         wheel_size = response.headers.get("content-length")
         operation_message = self.get_operation_message(operation)
         message = (
-            "  <fg=blue;options=bold>•</> {message}: <info>Downloading...</>".format(
-                message=operation_message,
-            )
+            f"  <fg=blue;options=bold>•</> {operation_message}: <info>Downloading...</>"
         )
         progress = None
         if self.supports_fancy_output():

src/poetry/installation/installer.py

@@ -17,6 +17,7 @@ from poetry.repositories import Repository
 from poetry.repositories.installed_repository import InstalledRepository
 from poetry.utils.extras import get_extra_package_names
 from poetry.utils.helpers import canonicalize_name
+from poetry.utils.helpers import pluralize
 
 
 if TYPE_CHECKING:
@@ -385,23 +386,13 @@ class Installer:
                     uninstalls += 1
 
             self._io.write_line("")
-            self._io.write_line(
-                "Package operations: "
-                "<info>{}</> install{}, "
-                "<info>{}</> update{}, "
-                "<info>{}</> removal{}"
-                "{}".format(
-                    installs,
-                    "" if installs == 1 else "s",
-                    updates,
-                    "" if updates == 1 else "s",
-                    uninstalls,
-                    "" if uninstalls == 1 else "s",
-                    f", <info>{skipped}</> skipped"
-                    if skipped and self.is_verbose()
-                    else "",
-                )
-            )
+            self._io.write("Package operations: ")
+            self._io.write(f"<info>{installs}</> install{pluralize(installs)}, ")
+            self._io.write(f"<info>{updates}</> update{pluralize(updates)}, ")
+            self._io.write(f"<info>{uninstalls}</> removal{pluralize(uninstalls)}")
+            if skipped and self.is_verbose():
+                self._io.write(f", <info>{skipped}</> skipped")
+            self._io.write_line("")
 
         self._io.write_line("")
 
@@ -419,23 +410,18 @@ class Installer:
         getattr(self, f"_execute_{method}")(operation)
 
     def _execute_install(self, operation: Install) -> None:
+        target = operation.package
         if operation.skipped:
             if self.is_verbose() and (self._execute_operations or self.is_dry_run()):
                 self._io.write_line(
-                    "  - Skipping <c1>{}</c1> (<c2>{}</c2>) {}".format(
-                        operation.package.pretty_name,
-                        operation.package.full_pretty_version,
-                        operation.skip_reason,
-                    )
+                    f"  - Skipping <c1>{target.pretty_name}</c1> (<c2>{target.full_pretty_version}</c2>) {operation.skip_reason}"
                 )
 
             return
 
         if self._execute_operations or self.is_dry_run():
             self._io.write_line(
-                "  - Installing <c1>{}</c1> (<c2>{}</c2>)".format(
-                    operation.package.pretty_name, operation.package.full_pretty_version
-                )
+                f"  - Installing <c1>{target.pretty_name}</c1> (<c2>{target.full_pretty_version}</c2>)"
             )
 
         if not self._execute_operations:
@@ -450,22 +436,16 @@ class Installer:
         if operation.skipped:
             if self.is_verbose() and (self._execute_operations or self.is_dry_run()):
                 self._io.write_line(
-                    "  - Skipping <c1>{}</c1> (<c2>{}</c2>) {}".format(
-                        target.pretty_name,
-                        target.full_pretty_version,
-                        operation.skip_reason,
-                    )
+                    f"  - Skipping <c1>{target.pretty_name}</c1> "
+                    f"(<c2>{target.full_pretty_version}</c2>) {operation.skip_reason}"
                 )
 
             return
 
         if self._execute_operations or self.is_dry_run():
             self._io.write_line(
-                "  - Updating <c1>{}</c1> (<c2>{}</c2> -> <c2>{}</c2>)".format(
-                    target.pretty_name,
-                    source.full_pretty_version,
-                    target.full_pretty_version,
-                )
+                f"  - Updating <c1>{target.pretty_name}</c1> "
+                f"(<c2>{source.full_pretty_version}</c2> -> <c2>{target.full_pretty_version}</c2>)"
             )
 
         if not self._execute_operations:
@@ -474,23 +454,18 @@ class Installer:
         self._installer.update(source, target)
 
     def _execute_uninstall(self, operation: Uninstall) -> None:
+        target = operation.package
         if operation.skipped:
             if self.is_verbose() and (self._execute_operations or self.is_dry_run()):
                 self._io.write_line(
-                    "  - Not removing <c1>{}</c1> (<c2>{}</c2>) {}".format(
-                        operation.package.pretty_name,
-                        operation.package.full_pretty_version,
-                        operation.skip_reason,
-                    )
+                    f"  - Not removing <c1>{target.pretty_name}</c1> (<c2>{target.pretty_version}</c2>) {operation.skip_reason}"
                 )
 
             return
 
         if self._execute_operations or self.is_dry_run():
             self._io.write_line(
-                "  - Removing <c1>{}</c1> (<c2>{}</c2>)".format(
-                    operation.package.pretty_name, operation.package.full_pretty_version
-                )
+                f"  - Removing <c1>{target.pretty_name}</c1> (<c2>{target.pretty_version}</c2>)"
             )
 
         if not self._execute_operations:

src/poetry/installation/operations/install.py

@@ -25,11 +25,7 @@ class Install(Operation):
         return "install"
 
     def __str__(self) -> str:
-        return "Installing {} ({})".format(
-            self.package.pretty_name, self.format_version(self.package)
-        )
+        return f"Installing {self.package.pretty_name} ({self.format_version(self.package)})"
 
     def __repr__(self) -> str:
-        return "<Install {} ({})>".format(
-            self.package.pretty_name, self.format_version(self.package)
-        )
+        return f"<Install {self.package.pretty_name} ({self.format_version(self.package)})>"

src/poetry/installation/operations/uninstall.py

@@ -28,11 +28,7 @@ class Uninstall(Operation):
         return "uninstall"
 
     def __str__(self) -> str:
-        return "Uninstalling {} ({})".format(
-            self.package.pretty_name, self.format_version(self._package)
-        )
+        return f"Uninstalling {self.package.pretty_name} ({self.format_version(self._package)})"
 
     def __repr__(self) -> str:
-        return "<Uninstall {} ({})>".format(
-            self.package.pretty_name, self.format_version(self.package)
-        )
+        return f"<Uninstall {self.package.pretty_name} ({self.format_version(self.package)})>"

src/poetry/installation/operations/update.py

@@ -38,17 +38,17 @@ class Update(Operation):
         return "update"
 
     def __str__(self) -> str:
-        return "Updating {} ({}) to {} ({})".format(
-            self.initial_package.pretty_name,
-            self.format_version(self.initial_package),
-            self.target_package.pretty_name,
-            self.format_version(self.target_package),
+        init_version = self.format_version(self.initial_package)
+        target_version = self.format_version(self.target_package)
+        return (
+            f"Updating {self.initial_package.pretty_name} ({init_version}) "
+            f"to {self.target_package.pretty_name} ({target_version})"
         )
 
     def __repr__(self) -> str:
-        return "<Update {} ({}) to {} ({})>".format(
-            self.initial_package.pretty_name,
-            self.format_version(self.initial_package),
-            self.target_package.pretty_name,
-            self.format_version(self.target_package),
+        init_version = self.format_version(self.initial_package)
+        target_version = self.format_version(self.target_package)
+        return (
+            f"<Update {self.initial_package.pretty_name} ({init_version}) "
+            f"to {self.target_package.pretty_name} ({target_version})>"
         )

src/poetry/installation/pip_installer.py

@@ -52,9 +52,7 @@ class PipInstaller(BaseInstaller):
             parsed = urllib.parse.urlparse(package.source_url)
             if parsed.scheme == "http":
                 self._io.write_error(
-                    "    <warning>Installing from unsecure host: {}</warning>".format(
-                        parsed.hostname
-                    )
+                    f"    <warning>Installing from unsecure host: {parsed.hostname}</warning>"
                 )
                 args += ["--trusted-host", parsed.hostname]
 
@@ -161,9 +159,7 @@ class PipInstaller(BaseInstaller):
             return req
 
         if package.source_type == "git":
-            req = "git+{}@{}#egg={}".format(
-                package.source_url, package.source_reference, package.name
-            )
+            req = f"git+{package.source_url}@{package.source_reference}#egg={package.name}"
 
             if package.develop:
                 req = ["-e", req]

src/poetry/json/__init__.py

@@ -31,9 +31,8 @@ def validate_object(obj: dict, schema_name: str) -> List[str]:
     for error in validation_errors:
         message = error.message
         if error.path:
-            message = "[{}] {}".format(
-                ".".join(str(x) for x in error.absolute_path), message
-            )
+            path = ".".join(str(x) for x in error.absolute_path)
+            message = f"[{path}] {message}"
 
         errors.append(message)
 

src/poetry/layouts/layout.py

@@ -61,10 +61,9 @@ class Layout:
 
         self._readme_format = readme_format.lower()
         if self._readme_format not in self.ACCEPTED_README_FORMATS:
+            accepted_readme_formats = ", ".join(self.ACCEPTED_README_FORMATS)
             raise ValueError(
-                "Invalid readme format '{}', use one of {}.".format(
-                    readme_format, ", ".join(self.ACCEPTED_README_FORMATS)
-                )
+                f"Invalid readme format '{readme_format}', use one of {accepted_readme_formats}."
             )
 
         self._license = license

src/poetry/masonry/builders/editable.py

@@ -47,9 +47,7 @@ class EditableBuilder(Builder):
 
     def build(self) -> None:
         self._debug(
-            "  - Building package <c1>{}</c1> in <info>editable</info> mode".format(
-                self._package.name
-            )
+            f"  - Building package <c1>{self._package.name}</c1> in <info>editable</info> mode"
         )
 
         if self._package.build_script:
@@ -65,9 +63,7 @@ class EditableBuilder(Builder):
             distribution_name=self._package.name
         ):
             self._debug(
-                "  - Removed <c2>{}</c2> directory from <b>{}</b>".format(
-                    removed.name, removed.parent
-                )
+                f"  - Removed <c2>{removed.name}</c2> directory from <b>{removed.parent}</b>"
             )
 
         added_files = []
@@ -128,9 +124,7 @@ class EditableBuilder(Builder):
         # remove any pre-existing pth files for this package
         for file in self._env.site_packages.find(path=pth_file, writable_only=True):
             self._debug(
-                "  - Removing existing <c2>{}</c2> from <b>{}</b> for {}".format(
-                    file.name, file.parent, self._poetry.file.parent
-                )
+                f"  - Removing existing <c2>{file.name}</c2> from <b>{file.parent}</b> for {self._poetry.file.parent}"
             )
             # We can't use unlink(missing_ok=True) because it's not always available
             if file.exists():
@@ -141,17 +135,13 @@ class EditableBuilder(Builder):
                 pth_file, content, encoding="utf-8"
             )
             self._debug(
-                "  - Adding <c2>{}</c2> to <b>{}</b> for {}".format(
-                    pth_file.name, pth_file.parent, self._poetry.file.parent
-                )
+                f"  - Adding <c2>{pth_file.name}</c2> to <b>{pth_file.parent}</b> for {self._poetry.file.parent}"
             )
             return [pth_file]
         except OSError:
             # TODO: Replace with PermissionError
             self._io.write_error_line(
-                "  - Failed to create <c2>{}</c2> for {}".format(
-                    pth_file.name, self._poetry.file.parent
-                )
+                f"  - Failed to create <c2>{pth_file.name}</c2> for {self._poetry.file.parent}"
             )
             return []
 
@@ -164,9 +154,7 @@ class EditableBuilder(Builder):
                 break
         else:
             self._io.write_error_line(
-                "  - Failed to find a suitable script installation directory for {}".format(
-                    self._poetry.file.parent
-                )
+                f"  - Failed to find a suitable script installation directory for {self._poetry.file.parent}"
             )
             return []
 
@@ -178,9 +166,7 @@ class EditableBuilder(Builder):
 
             script_file = scripts_path.joinpath(name)
             self._debug(
-                "  - Adding the <c2>{}</c2> script to <b>{}</b>".format(
-                    name, scripts_path
-                )
+                f"  - Adding the <c2>{name}</c2> script to <b>{scripts_path}</b>"
             )
             with script_file.open("w", encoding="utf-8") as f:
                 f.write(
@@ -202,9 +188,7 @@ class EditableBuilder(Builder):
                 cmd_script = script_file.with_suffix(".cmd")
                 cmd = WINDOWS_CMD_TEMPLATE.format(python=self._env.python, script=name)
                 self._debug(
-                    "  - Adding the <c2>{}</c2> script wrapper to <b>{}</b>".format(
-                        cmd_script.name, scripts_path
-                    )
+                    f"  - Adding the <c2>{cmd_script.name}</c2> script wrapper to <b>{scripts_path}</b>"
                 )
 
                 with cmd_script.open("w", encoding="utf-8") as f:
@@ -223,9 +207,7 @@ class EditableBuilder(Builder):
         dist_info = self._env.site_packages.mkdir(Path(builder.dist_info))
 
         self._debug(
-            "  - Adding the <c2>{}</c2> directory to <b>{}</b>".format(
-                dist_info.name, dist_info.parent
-            )
+            f"  - Adding the <c2>{dist_info.name}</c2> directory to <b>{dist_info.parent}</b>"
         )
 
         with dist_info.joinpath("METADATA").open("w", encoding="utf-8") as f:
@@ -246,14 +228,15 @@ class EditableBuilder(Builder):
 
             added_files.append(dist_info.joinpath("entry_points.txt"))
 
-        with dist_info.joinpath("RECORD").open("w", encoding="utf-8") as f:
+        record = dist_info.joinpath("RECORD")
+        with record.open("w", encoding="utf-8") as f:
             for path in added_files:
                 hash = self._get_file_hash(path)
                 size = path.stat().st_size
-                f.write(f"{str(path)},sha256={hash},{size}\n")
+                f.write(f"{path!s},sha256={hash},{size}\n")
 
             # RECORD itself is recorded with no hash or size
-            f.write("{},,\n".format(dist_info.joinpath("RECORD")))
+            f.write(f"{record},,\n")
 
     def _get_file_hash(self, filepath: Path) -> str:
         hashsum = hashlib.sha256()

src/poetry/mixology/failure.py

@@ -43,11 +43,9 @@ class _Writer:
             if isinstance(incompatibility.cause, PythonCause):
                 if not required_python_version_notification:
                     buffer.append(
-                        "The current project's Python requirement ({}) "
+                        f"The current project's Python requirement ({incompatibility.cause.root_python_version}) "
                         "is not compatible with some of the required "
-                        "packages Python requirement:".format(
-                            incompatibility.cause.root_python_version
-                        )
+                        "packages Python requirement:"
                     )
                     required_python_version_notification = True
 
@@ -56,11 +54,9 @@ class _Writer:
                 )
                 constraint = parse_constraint(incompatibility.cause.python_version)
                 buffer.append(
-                    "  - {} requires Python {}, so it will not be satisfied for Python {}".format(
-                        incompatibility.terms[0].dependency.name,
-                        incompatibility.cause.python_version,
-                        root_constraint.difference(constraint),
-                    )
+                    f"  - {incompatibility.terms[0].dependency.name} requires Python "
+                    f"{incompatibility.cause.python_version}, so it will not be satisfied "
+                    f"for Python {root_constraint.difference(constraint)}"
                 )
 
         if required_python_version_notification:
@@ -128,14 +124,12 @@ class _Writer:
             other_line = self._line_numbers.get(cause.other)
 
             if conflict_line is not None and other_line is not None:
+                reason = cause.conflict.and_to_string(
+                    cause.other, details_for_cause, conflict_line, other_line
+                )
                 self._write(
                     incompatibility,
-                    "Because {}, {}.".format(
-                        cause.conflict.and_to_string(
-                            cause.other, details_for_cause, conflict_line, other_line
-                        ),
-                        incompatibility_string,
-                    ),
+                    f"Because {reason}, {incompatibility_string}.",
                     numbered=numbered,
                 )
             elif conflict_line is not None or other_line is not None:
@@ -151,9 +145,7 @@ class _Writer:
                 self._visit(without_line, details_for_cause)
                 self._write(
                     incompatibility,
-                    "{} because {} ({}), {}.".format(
-                        conjunction, str(with_line), line, incompatibility_string
-                    ),
+                    f"{conjunction} because {with_line!s} ({line}), {incompatibility_string}.",
                     numbered=numbered,
                 )
             else:
@@ -178,12 +170,7 @@ class _Writer:
 
                     self._write(
                         incompatibility,
-                        "{} because {} ({}), {}".format(
-                            conjunction,
-                            str(cause.conflict),
-                            self._line_numbers[cause.conflict],
-                            incompatibility_string,
-                        ),
+                        f"{conjunction} because {cause.conflict!s} ({self._line_numbers[cause.conflict]}), {incompatibility_string}",
                         numbered=numbered,
                     )
         elif isinstance(cause.conflict.cause, ConflictCause) or isinstance(
@@ -202,14 +189,12 @@ class _Writer:
 
             derived_line = self._line_numbers.get(derived)
             if derived_line is not None:
+                reason = ext.and_to_string(
+                    derived, details_for_cause, None, derived_line
+                )
                 self._write(
                     incompatibility,
-                    "Because {}, {}.".format(
-                        ext.and_to_string(
-                            derived, details_for_cause, None, derived_line
-                        ),
-                        incompatibility_string,
-                    ),
+                    f"Because {reason}, {incompatibility_string}.",
                     numbered=numbered,
                 )
             elif self._is_collapsible(derived):
@@ -227,33 +212,26 @@ class _Writer:
                 details_for_cause = {}
 
                 self._visit(collapsed_derived, details_for_cause)
+                reason = collapsed_ext.and_to_string(ext, details_for_cause, None, None)
                 self._write(
                     incompatibility,
-                    "{} because {}, {}.".format(
-                        conjunction,
-                        collapsed_ext.and_to_string(ext, details_for_cause, None, None),
-                        incompatibility_string,
-                    ),
+                    f"{conjunction} because {reason}, {incompatibility_string}.",
                     numbered=numbered,
                 )
             else:
                 self._visit(derived, details_for_cause)
                 self._write(
                     incompatibility,
-                    "{} because {}, {}.".format(
-                        conjunction, str(ext), incompatibility_string
-                    ),
+                    f"{conjunction} because {ext!s}, {incompatibility_string}.",
                     numbered=numbered,
                 )
         else:
+            reason = cause.conflict.and_to_string(
+                cause.other, details_for_cause, None, None
+            )
             self._write(
                 incompatibility,
-                "Because {}, {}.".format(
-                    cause.conflict.and_to_string(
-                        cause.other, details_for_cause, None, None
-                    ),
-                    incompatibility_string,
-                ),
+                f"Because {reason}, {incompatibility_string}.",
                 numbered=numbered,
             )
 

src/poetry/mixology/incompatibility.py

@@ -130,9 +130,7 @@ class Incompatibility:
             assert depender.is_positive()
             assert not dependee.is_positive()
 
-            return "{} depends on {}".format(
-                self._terse(depender, allow_every=True), self._terse(dependee)
-            )
+            return f"{self._terse(depender, allow_every=True)} depends on {self._terse(dependee)}"
         elif isinstance(self._cause, PythonCause):
             assert len(self._terms) == 1
             assert self._terms[0].is_positive()
@@ -155,9 +153,7 @@ class Incompatibility:
             assert len(self._terms) == 1
             assert self._terms[0].is_positive()
 
-            return "no versions of {} match {}".format(
-                self._terms[0].dependency.name, self._terms[0].constraint
-            )
+            return f"no versions of {self._terms[0].dependency.name} match {self._terms[0].constraint}"
         elif isinstance(self._cause, PackageNotFoundCause):
             assert len(self._terms) == 1
             assert self._terms[0].is_positive()
@@ -168,18 +164,14 @@ class Incompatibility:
             assert not self._terms[0].is_positive()
             assert self._terms[0].dependency.is_root
 
-            return "{} is {}".format(
-                self._terms[0].dependency.name, self._terms[0].dependency.constraint
-            )
+            return f"{self._terms[0].dependency.name} is {self._terms[0].dependency.constraint}"
         elif self.is_failure():
             return "version solving failed"
 
         if len(self._terms) == 1:
             term = self._terms[0]
-            return "{} is {}".format(
-                term.dependency.name,
-                "forbidden" if term.is_positive() else "required",
-            )
+            verb = "forbidden" if term.is_positive() else "required"
+            return f"{term.dependency.name} is {verb}"
 
         if len(self._terms) == 2:
             term1 = self._terms[0]
@@ -200,9 +192,7 @@ class Incompatibility:
 
                     return f"{package1} is incompatible with {package2}"
                 else:
-                    return "either {} or {}".format(
-                        self._terse(term1), self._terse(term2)
-                    )
+                    return f"either {self._terse(term1)} or {self._terse(term2)}"
 
         positive = []
         negative = []
@@ -217,17 +207,13 @@ class Incompatibility:
             if len(positive) == 1:
                 positive_term = [term for term in self._terms if term.is_positive()][0]
 
-                return "{} requires {}".format(
-                    self._terse(positive_term, allow_every=True), " or ".join(negative)
-                )
+                return f"{self._terse(positive_term, allow_every=True)} requires {' or '.join(negative)}"
             else:
-                return "if {} then {}".format(
-                    " and ".join(positive), " or ".join(negative)
-                )
+                return f"if {' and '.join(positive)} then {' or '.join(negative)}"
         elif positive:
-            return "one of {} must be false".format(" or ".join(positive))
+            return f"one of {' or '.join(positive)} must be false"
         else:
-            return "one of {} must be true".format(" or ".join(negative))
+            return f"one of {' or '.join(negative)} must be true"
 
     def and_to_string(
         self,
@@ -254,12 +240,12 @@ class Incompatibility:
 
         buffer = [str(self)]
         if this_line is not None:
-            buffer.append(" " + str(this_line))
+            buffer.append(f" {this_line!s}")
 
-        buffer.append(f" and {str(other)}")
+        buffer.append(f" and {other!s}")
 
         if other_line is not None:
-            buffer.append(" " + str(other_line))
+            buffer.append(f" {other_line!s}")
 
         return "\n".join(buffer)
 
@@ -454,9 +440,7 @@ class Incompatibility:
         if term.dependency.is_root:
             return term.dependency.pretty_name
 
-        return "{} ({})".format(
-            term.dependency.pretty_name, term.dependency.pretty_constraint
-        )
+        return f"{term.dependency.pretty_name} ({term.dependency.pretty_constraint})"
 
     def _single_term_where(
         self, callable: Callable[["Term"], bool]
@@ -474,4 +458,4 @@ class Incompatibility:
         return found
 
     def __repr__(self) -> str:
-        return f"<Incompatibility {str(self)}>"
+        return f"<Incompatibility {self!s}>"

src/poetry/mixology/solutions/solutions/python_requirement_solution.py

@@ -26,11 +26,9 @@ class PythonRequirementSolution(Solution):
                 constraint = parse_constraint(incompatibility.cause.python_version)
 
                 version_solutions.append(
-                    "For <fg=default;options=bold>{}</>, a possible solution would be "
-                    'to set the `<fg=default;options=bold>python</>` property to <fg=yellow>"{}"</>'.format(
-                        incompatibility.terms[0].dependency.name,
-                        root_constraint.intersect(constraint),
-                    )
+                    f"For <fg=default;options=bold>{incompatibility.terms[0].dependency.name}</>, "
+                    "a possible solution would be to set the `<fg=default;options=bold>python</>` "
+                    f'property to <fg=yellow>"{root_constraint.intersect(constraint)}"</>'
                 )
 
         description = (

src/poetry/mixology/term.py

@@ -162,7 +162,8 @@ class Term:
         return Term(self.dependency.with_constraint(constraint), is_positive)
 
     def __str__(self) -> str:
-        return "{}{}".format("not " if not self.is_positive() else "", self._dependency)
+        prefix = "not " if not self.is_positive() else ""
+        return f"{prefix}{self._dependency}"
 
     def __repr__(self) -> str:
-        return f"<Term {str(self)}>"
+        return f"<Term {self!s}>"

src/poetry/mixology/version_solver.py

@@ -87,10 +87,8 @@ class VersionSolver:
             raise
         finally:
             self._log(
-                "Version solving took {:.3f} seconds.\n"
-                "Tried {} solutions.".format(
-                    time.time() - start, self._solution.attempted_solutions
-                )
+                f"Version solving took {time.time() - start:.3f} seconds.\n"
+                f"Tried {self._solution.attempted_solutions} solutions."
             )
 
     def _propagate(self, package: str) -> None:
@@ -172,11 +170,8 @@ class VersionSolver:
         if unsatisfied is None:
             return _conflict
 
-        self._log(
-            "derived: {}{}".format(
-                "not " if unsatisfied.is_positive() else "", unsatisfied.dependency
-            )
-        )
+        adverb = "not " if unsatisfied.is_positive() else ""
+        self._log(f"derived: {adverb}{unsatisfied.dependency}")
 
         self._solution.derive(
             unsatisfied.dependency, not unsatisfied.is_positive(), incompatibility
@@ -304,14 +299,11 @@ class VersionSolver:
             new_incompatibility = True
 
             partially = "" if difference is None else " partially"
-            bang = "!"
             self._log(
-                "{} {} is{} satisfied by {}".format(
-                    bang, most_recent_term, partially, most_recent_satisfier
-                )
+                f"! {most_recent_term} is{partially} satisfied by {most_recent_satisfier}"
             )
-            self._log(f'{bang} which is caused by "{most_recent_satisfier.cause}"')
-            self._log(f"{bang} thus: {incompatibility}")
+            self._log(f'! which is caused by "{most_recent_satisfier.cause}"')
+            self._log(f"! thus: {incompatibility}")
 
         raise SolveFailure(incompatibility)
 
@@ -412,9 +404,7 @@ class VersionSolver:
         if not conflict:
             self._solution.decide(version)
             self._log(
-                "selecting {} ({})".format(
-                    version.complete_name, version.full_pretty_version
-                )
+                f"selecting {version.complete_name} ({version.full_pretty_version})"
             )
 
         return dependency.complete_name

src/poetry/publishing/publisher.py

@@ -67,9 +67,7 @@ class Publisher:
                 auth = self._authenticator.get_http_auth(repository_name)
                 if auth:
                     logger.debug(
-                        "Found authentication information for {}.".format(
-                            repository_name
-                        )
+                        f"Found authentication information for {repository_name}."
                     )
                     username = auth["username"]
                     password = auth["password"]
@@ -88,13 +86,11 @@ class Publisher:
 
         self._uploader.auth(username, password)
 
+        if repository_name == "pypi":
+            repository_name = "PyPI"
         self._io.write_line(
-            "Publishing <c1>{}</c1> (<c2>{}</c2>) "
-            "to <info>{}</info>".format(
-                self._package.pretty_name,
-                self._package.pretty_version,
-                "PyPI" if repository_name == "pypi" else repository_name,
-            )
+            f"Publishing <c1>{self._package.pretty_name}</c1> (<c2>{self._package.pretty_version}</c2>) "
+            f"to <info>{repository_name}</info>"
         )
 
         self._uploader.upload(

src/poetry/publishing/uploader.py

@@ -335,4 +335,4 @@ class Uploader:
         elif len(exts) >= 2 and "".join(exts[-2:]) == ".tar.gz":
             return "sdist"
 
-        raise ValueError("Unknown distribution format {}".format("".join(exts)))
+        raise ValueError("Unknown distribution format " + "".join(exts))

src/poetry/puzzle/provider.py

@@ -216,9 +216,8 @@ class Provider:
         if vcs != "git":
             raise ValueError(f"Unsupported VCS dependency {vcs}")
 
-        tmp_dir = Path(
-            mkdtemp(prefix="pypoetry-git-{}".format(url.split("/")[-1].rstrip(".git")))
-        )
+        suffix = url.split("/")[-1].rstrip(".git")
+        tmp_dir = Path(mkdtemp(prefix=f"pypoetry-git-{suffix}"))
 
         try:
             git = Git()
@@ -259,9 +258,7 @@ class Provider:
         if dependency.name != package.name:
             # For now, the dependency's name must match the actual package's name
             raise RuntimeError(
-                "The dependency name for {} does not match the actual package's name: {}".format(
-                    dependency.name, package.name
-                )
+                f"The dependency name for {dependency.name} does not match the actual package's name: {package.name}"
             )
 
         if dependency.base is not None:
@@ -321,9 +318,7 @@ class Provider:
         if name and name != package.name:
             # For now, the dependency's name must match the actual package's name
             raise RuntimeError(
-                "The dependency name for {} does not match the actual package's name: {}".format(
-                    name, package.name
-                )
+                f"The dependency name for {name} does not match the actual package's name: {package.name}"
             )
 
         return package
@@ -337,9 +332,7 @@ class Provider:
         if dependency.name != package.name:
             # For now, the dependency's name must match the actual package's name
             raise RuntimeError(
-                "The dependency name for {} does not match the actual package's name: {}".format(
-                    dependency.name, package.name
-                )
+                f"The dependency name for {dependency.name} does not match the actual package's name: {package.name}"
             )
 
         for extra in dependency.extras:
@@ -596,7 +589,7 @@ class Provider:
                 continue
 
             if len(by_constraint) == 1:
-                self.debug(f"<debug>Merging requirements for {str(deps[0])}</debug>")
+                self.debug(f"<debug>Merging requirements for {deps[0]!s}</debug>")
                 dependencies.append(list(by_constraint.values())[0][0])
                 continue
 
@@ -633,28 +626,19 @@ class Provider:
             # with the following overrides:
             #   - {<Package foo (1.2.3): {"bar": <Dependency bar (>=2.0)>}
             #   - {<Package foo (1.2.3): {"bar": <Dependency bar (<2.0)>}
-            markers = []
-            for deps in by_constraint.values():
-                markers.append(deps[0].marker)
-
             _deps = [_dep[0] for _dep in by_constraint.values()]
-            self.debug(
-                "<warning>Different requirements found for {}.</warning>".format(
-                    ", ".join(
-                        "<c1>{}</c1> <fg=default>(<c2>{}</c2>)</> with markers <b>{}</b>".format(
-                            d.name,
-                            d.pretty_constraint,
-                            d.marker if not d.marker.is_any() else "*",
-                        )
-                        for d in _deps[:-1]
-                    )
-                    + " and "
-                    + "<c1>{}</c1> <fg=default>(<c2>{}</c2>)</> with markers <b>{}</b>".format(
-                        _deps[-1].name,
-                        _deps[-1].pretty_constraint,
-                        _deps[-1].marker if not _deps[-1].marker.is_any() else "*",
-                    )
+
+            def fmt_warning(d: "Dependency") -> str:
+                marker = d.marker if not d.marker.is_any() else "*"
+                return (
+                    f"<c1>{d.name}</c1> <fg=default>(<c2>{d.pretty_constraint}</c2>)</> "
+                    f"with markers <b>{marker}</b>"
                 )
+
+            warnings = ", ".join(fmt_warning(d) for d in _deps[:-1])
+            warnings += f" and {fmt_warning(_deps[-1])}"
+            self.debug(
+                f"<warning>Different requirements found for {warnings}.</warning>"
             )
 
             # We need to check if one of the duplicate dependencies
@@ -758,10 +742,8 @@ class Provider:
                     version = ""
 
                 message = (
-                    "<fg=blue>fact</>: <c1>{}</c1>{} "
-                    "depends on <c1>{}</c1> (<c2>{}</c2>)".format(
-                        name, version, m.group(2), m.group(3)
-                    )
+                    f"<fg=blue>fact</>: <c1>{name}</c1>{version} "
+                    f"depends on <c1>{m.group(2)}</c1> (<c2>{m.group(3)}</c2>)"
                 )
             elif " is " in message:
                 message = re.sub(
@@ -773,7 +755,7 @@ class Provider:
                 message = re.sub(
                     r"(?<=: )(.+?) \((.+?)\)", "<c1>\\1</c1> (<c2>\\2</c2>)", message
                 )
-                message = "<fg=blue>fact</>: {}".format(message.split("fact: ")[1])
+                message = f"<fg=blue>fact</>: {message.split('fact: ')[1]}"
         elif message.startswith("selecting "):
             message = re.sub(
                 r"selecting (.+?) \((.+?)\)",
@@ -783,12 +765,10 @@ class Provider:
         elif message.startswith("derived:"):
             m = re.match(r"derived: (.+?) \((.+?)\)$", message)
             if m:
-                message = "<fg=blue>derived</>: <c1>{}</c1> (<c2>{}</c2>)".format(
-                    m.group(1), m.group(2)
-                )
+                message = f"<fg=blue>derived</>: <c1>{m.group(1)}</c1> (<c2>{m.group(2)}</c2>)"
             else:
-                message = "<fg=blue>derived</>: <c1>{}</c1>".format(
-                    message.split("derived: ")[1]
+                message = (
+                    f"<fg=blue>derived</>: <c1>{message.split('derived: ')[1]}</c1>"
                 )
         elif message.startswith("conflict:"):
             m = re.match(r"conflict: (.+?) depends on (.+?) \((.+?)\)", message)
@@ -802,15 +782,11 @@ class Provider:
                     version = ""
 
                 message = (
-                    "<fg=red;options=bold>conflict</>: <c1>{}</c1>{} "
-                    "depends on <c1>{}</c1> (<c2>{}</c2>)".format(
-                        name, version, m.group(2), m.group(3)
-                    )
+                    f"<fg=red;options=bold>conflict</>: <c1>{name}</c1>{version} "
+                    f"depends on <c1>{m.group(2)}</c1> (<c2>{m.group(3)}</c2>)"
                 )
             else:
-                message = "<fg=red;options=bold>conflict</>: {}".format(
-                    message.split("conflict: ")[1]
-                )
+                message = f"<fg=red;options=bold>conflict</>: {message.split('conflict: ')[1]}"
 
         message = message.replace("! ", "<error>!</error> ")
 

src/poetry/puzzle/solver.py

@@ -78,9 +78,7 @@ class Solver:
 
             if len(self._overrides) > 1:
                 self._provider.debug(
-                    "Complete version solving took {:.3f} seconds with {} overrides".format(
-                        end - start, len(self._overrides)
-                    )
+                    f"Complete version solving took {end - start:.3f} seconds with {len(self._overrides)} overrides"
                 )
                 self._provider.debug(
                     f"Resolved with overrides: {', '.join(f'({b})' for b in self._overrides)}"

src/poetry/repositories/legacy_repository.py

@@ -145,7 +145,7 @@ class Page:
         """Makes sure a link is fully encoded.  That is, if a ' ' shows up in
         the link, it will be rewritten to %20 (while not over-quoting
         % or other characters)."""
-        return self._clean_re.sub(lambda match: "%%%2x" % ord(match.group(0)), url)
+        return self._clean_re.sub(lambda match: f"%{match.group(0):2x}", url)
 
 
 # TODO: revisit whether the LegacyRepository should inherit from PyPiRepository.
@@ -217,14 +217,10 @@ class LegacyRepository(PyPiRepository):
             return self.url
 
         parsed = urllib.parse.urlparse(self.url)
+        username = quote(self._session.auth.username, safe="")
+        password = quote(self._session.auth.password, safe="")
 
-        return "{scheme}://{username}:{password}@{netloc}{path}".format(
-            scheme=parsed.scheme,
-            username=quote(self._session.auth.username, safe=""),
-            password=quote(self._session.auth.password, safe=""),
-            netloc=parsed.netloc,
-            path=parsed.path,
-        )
+        return f"{parsed.scheme}://{username}:{password}@{parsed.netloc}{parsed.path}"
 
     def find_packages(self, dependency: "Dependency") -> List[Package]:
         packages = []
@@ -247,14 +243,14 @@ class LegacyRepository(PyPiRepository):
 
         key = dependency.name
         if not constraint.is_any():
-            key = f"{key}:{str(constraint)}"
+            key = f"{key}:{constraint!s}"
 
         ignored_pre_release_versions = []
 
         if self._cache.store("matches").has(key):
             versions = self._cache.store("matches").get(key)
         else:
-            page = self._get_page("/{}/".format(dependency.name.replace(".", "-")))
+            page = self._get_page(f"/{dependency.name.replace('.', '-')}/")
             if page is None:
                 return []
 
@@ -284,9 +280,7 @@ class LegacyRepository(PyPiRepository):
                 packages.append(package)
 
             self._log(
-                "{} packages found for {} {}".format(
-                    len(packages), dependency.name, str(constraint)
-                ),
+                f"{len(packages)} packages found for {dependency.name} {constraint!s}",
                 level="debug",
             )
 
@@ -323,14 +317,14 @@ class LegacyRepository(PyPiRepository):
             return package
 
     def find_links_for_package(self, package: Package) -> List[Link]:
-        page = self._get_page("/{}/".format(package.name.replace(".", "-")))
+        page = self._get_page(f"/{package.name.replace('.', '-')}/")
         if page is None:
             return []
 
         return list(page.links_for_version(package.version))
 
     def _get_release_info(self, name: str, version: str) -> dict:
-        page = self._get_page("/{}/".format(canonicalize_name(name).replace(".", "-")))
+        page = self._get_page(f"/{canonicalize_name(name).replace('.', '-')}/")
         if page is None:
             raise PackageNotFound(f'No package named "{name}"')
 
@@ -348,9 +342,7 @@ class LegacyRepository(PyPiRepository):
         links = list(page.links_for_version(Version.parse(version)))
         if not links:
             raise PackageNotFound(
-                'No valid distribution links found for package: "{}" version: "{}"'.format(
-                    name, version
-                )
+                f'No valid distribution links found for package: "{name}" version: "{version}"'
             )
         urls = defaultdict(list)
         files = []
@@ -388,9 +380,7 @@ class LegacyRepository(PyPiRepository):
                             required_hash.update(chunk)
 
                     if not known_hash or known_hash.hexdigest() == link.hash:
-                        file_hash = "{}:{}".format(
-                            required_hash.name, required_hash.hexdigest()
-                        )
+                        file_hash = f"{required_hash.name}:{required_hash.hexdigest()}"
 
             files.append({"file": link.filename, "hash": file_hash})
 
@@ -422,9 +412,7 @@ class LegacyRepository(PyPiRepository):
 
         if response.url != url:
             self._log(
-                "Response URL {response_url} differs from request URL {url}".format(
-                    response_url=response.url, url=url
-                ),
+                f"Response URL {response.url} differs from request URL {url}",
                 level="debug",
             )
 

src/poetry/repositories/pypi_repository.py

@@ -109,7 +109,7 @@ class PyPiRepository(RemoteRepository):
             info = self.get_package_info(dependency.name)
         except PackageNotFound:
             self._log(
-                f"No packages found for {dependency.name} {str(constraint)}",
+                f"No packages found for {dependency.name} {constraint!s}",
                 level="debug",
             )
             return []
@@ -121,9 +121,7 @@ class PyPiRepository(RemoteRepository):
             if not release:
                 # Bad release
                 self._log(
-                    "No release information found for {}-{}, skipping".format(
-                        dependency.name, version
-                    ),
+                    f"No release information found for {dependency.name}-{version}, skipping",
                     level="debug",
                 )
                 continue
@@ -132,9 +130,7 @@ class PyPiRepository(RemoteRepository):
                 package = Package(info["info"]["name"], version)
             except InvalidVersion:
                 self._log(
-                    'Unable to parse version "{}" for the {} package, skipping'.format(
-                        version, dependency.name
-                    ),
+                    f'Unable to parse version "{version}" for the {dependency.name} package, skipping',
                     level="debug",
                 )
                 continue
@@ -149,9 +145,7 @@ class PyPiRepository(RemoteRepository):
                 packages.append(package)
 
         self._log(
-            "{} packages found for {} {}".format(
-                len(packages), dependency.name, str(constraint)
-            ),
+            f"{len(packages)} packages found for {dependency.name} {constraint!s}",
             level="debug",
         )
 
@@ -189,9 +183,7 @@ class PyPiRepository(RemoteRepository):
                 results.append(result)
             except InvalidVersion:
                 self._log(
-                    'Unable to parse version "{}" for the {} package, skipping'.format(
-                        version, name
-                    ),
+                    f'Unable to parse version "{version}" for the {name} package, skipping',
                     level="debug",
                 )
 
@@ -254,7 +246,7 @@ class PyPiRepository(RemoteRepository):
 
         links = []
         for url in json_data["urls"]:
-            h = "sha256={}".format(url["digests"]["sha256"])
+            h = f"sha256={url['digests']['sha256']}"
             links.append(Link(url["url"] + "#" + h))
 
         return links
@@ -433,14 +425,9 @@ class PyPiRepository(RemoteRepository):
     def _get_info_from_wheel(self, url: str) -> "PackageInfo":
         from poetry.inspection.info import PackageInfo
 
-        self._log(
-            "Downloading wheel: {}".format(
-                urllib.parse.urlparse(url).path.rsplit("/")[-1]
-            ),
-            level="debug",
-        )
-
-        filename = os.path.basename(urllib.parse.urlparse(url).path.rsplit("/")[-1])
+        wheel_name = urllib.parse.urlparse(url).path.rsplit("/")[-1]
+        self._log(f"Downloading wheel: {wheel_name}", level="debug")
+        filename = os.path.basename(wheel_name)
 
         with temporary_directory() as temp_dir:
             filepath = Path(temp_dir) / filename
@@ -451,14 +438,9 @@ class PyPiRepository(RemoteRepository):
     def _get_info_from_sdist(self, url: str) -> "PackageInfo":
         from poetry.inspection.info import PackageInfo
 
-        self._log(
-            "Downloading sdist: {}".format(
-                urllib.parse.urlparse(url).path.rsplit("/")[-1]
-            ),
-            level="debug",
-        )
-
-        filename = os.path.basename(urllib.parse.urlparse(url).path)
+        sdist_name = urllib.parse.urlparse(url).path
+        self._log(f"Downloading sdist: {sdist_name.rsplit('/')[-1]}", level="debug")
+        filename = os.path.basename(sdist_name)
 
         with temporary_directory() as temp_dir:
             filepath = Path(temp_dir) / filename

src/poetry/utils/authenticator.py

@@ -35,11 +35,7 @@ class Authenticator:
 
     def _log(self, message: str, level: str = "debug") -> None:
         if self._io is not None:
-            self._io.write_line(
-                "<{level:s}>{message:s}</{level:s}>".format(
-                    message=message, level=level
-                )
-            )
+            self._io.write_line(f"<{level}>{message}</{level}>")
         else:
             getattr(logger, level, logger.debug)(message)
 

src/poetry/utils/env.py

@@ -254,19 +254,16 @@ class SitePackages:
                 except ValueError:
                     pass
             else:
+                site_type = "writable " if writable_only else ""
                 raise ValueError(
-                    "{} is not relative to any discovered {}sites".format(
-                        path, "writable " if writable_only else ""
-                    )
+                    f"{path} is not relative to any discovered {site_type}sites"
                 )
 
         results = [candidate / path for candidate in candidates if candidate]
 
         if not results and strict:
             raise RuntimeError(
-                'Unable to find a suitable destination for "{}" in {}'.format(
-                    str(path), paths_csv(self._candidates)
-                )
+                f'Unable to find a suitable destination for "{path}" in {paths_csv(self._candidates)}'
             )
 
         return results
@@ -421,9 +418,7 @@ class EnvCommandError(EnvError):
     def __init__(self, e: CalledProcessError, input: Optional[str] = None) -> None:
         self.e = e
 
-        message = "Command {} errored with the following return code {}, and output: \n{}".format(
-            e.cmd, e.returncode, decode(e.output)
-        )
+        message = f"Command {e.cmd} errored with the following return code {e.returncode}, and output: \n{decode(e.output)}"
         if input:
             message += f"input was : {input}"
         super().__init__(message)
@@ -433,11 +428,11 @@ class NoCompatiblePythonVersionFound(EnvError):
     def __init__(self, expected: str, given: Optional[str] = None) -> None:
         if given:
             message = (
-                "The specified Python version ({}) "
-                "is not supported by the project ({}).\n"
+                f"The specified Python version ({given}) "
+                f"is not supported by the project ({expected}).\n"
                 "Please choose a compatible version "
                 "or loosen the python constraint specified "
-                "in the pyproject.toml file.".format(given, expected)
+                "in the pyproject.toml file."
             )
         else:
             message = (
@@ -573,11 +568,8 @@ class EnvManager:
             envs = envs_file.read()
             env = envs.get(name)
             if env is not None:
-                io.write_line(
-                    "Deactivating virtualenv: <comment>{}</comment>".format(
-                        venv_path / (name + "-py{}".format(env["minor"]))
-                    )
-                )
+                venv = venv_path / f"{name}-py{env['minor']}"
+                io.write_line(f"Deactivating virtualenv: <comment>{venv}</comment>")
                 del envs[name]
 
                 envs_file.write(envs)
@@ -834,11 +826,9 @@ class EnvManager:
                 )
 
             io.write_line(
-                "<warning>The currently activated Python version {} "
-                "is not supported by the project ({}).\n"
-                "Trying to find and use a compatible version.</warning> ".format(
-                    python_patch, self._poetry.package.python_versions
-                )
+                f"<warning>The currently activated Python version {python_patch} "
+                f"is not supported by the project ({self._poetry.package.python_versions}).\n"
+                "Trying to find and use a compatible version.</warning> "
             )
 
             for python_to_try in sorted(
@@ -910,17 +900,15 @@ class EnvManager:
 
                 return self.get_system_env()
 
-            io.write_line(f"Creating virtualenv <c1>{name}</> in {str(venv_path)}")
+            io.write_line(f"Creating virtualenv <c1>{name}</> in {venv_path!s}")
         else:
             create_venv = False
             if force:
                 if not env.is_sane():
                     io.write_line(
-                        "<warning>The virtual environment found in {} seems to be broken.</warning>".format(
-                            env.path
-                        )
+                        f"<warning>The virtual environment found in {env.path} seems to be broken.</warning>"
                     )
-                io.write_line(f"Recreating virtualenv <c1>{name}</> in {str(venv)}")
+                io.write_line(f"Recreating virtualenv <c1>{name}</> in {venv!s}")
                 self.remove_venv(venv)
                 create_venv = True
             elif io.is_very_verbose():
@@ -1493,7 +1481,7 @@ class SystemEnv(Env):
     def get_marker_env(self) -> Dict[str, Any]:
         if hasattr(sys, "implementation"):
             info = sys.implementation.version
-            iver = "{0.major}.{0.minor}.{0.micro}".format(info)
+            iver = f"{info.major}.{info.minor}.{info.micro}"
             kind = info.releaselevel
             if kind != "final":
                 iver += kind[0] + str(info.serial)
@@ -1678,8 +1666,8 @@ class GenericEnv(VirtualEnv):
         patterns = [("python*", "pip*")]
 
         if self._child_env:
-            minor_version = "{}.{}".format(
-                self._child_env.version_info[0], self._child_env.version_info[1]
+            minor_version = (
+                f"{self._child_env.version_info[0]}.{self._child_env.version_info[1]}"
             )
             major_version = f"{self._child_env.version_info[0]}"
             patterns = [

src/poetry/utils/exporter.py

@@ -45,7 +45,7 @@ class Exporter:
         if fmt not in self.ACCEPTED_FORMATS:
             raise ValueError(f"Invalid export format: {fmt}")
 
-        getattr(self, "_export_{}".format(fmt.replace(".", "_")))(
+        getattr(self, "_export_" + fmt.replace(".", "_"))(
             cwd,
             output,
             with_hashes=with_hashes,
@@ -120,11 +120,8 @@ class Exporter:
                     hashes.append(f"{algorithm}:{h}")
 
                 if hashes:
-                    line += " \\\n"
-                    for i, h in enumerate(hashes):
-                        line += "    --hash={}{}".format(
-                            h, " \\\n" if i < len(hashes) - 1 else ""
-                        )
+                    sep = " \\\n"
+                    line += sep + sep.join(f"    --hash={h}" for h in hashes)
             dependency_lines.add(line)
 
         content += "\n".join(sorted(dependency_lines))

src/poetry/utils/helpers.py

@@ -110,16 +110,14 @@ def get_package_version_display_string(
     package: "Package", root: Optional[Path] = None
 ) -> str:
     if package.source_type in ["file", "directory"] and root:
-        return "{} {}".format(
-            package.version,
-            Path(os.path.relpath(package.source_url, root.as_posix())).as_posix(),
-        )
+        path = Path(os.path.relpath(package.source_url, root.as_posix())).as_posix()
+        return f"{package.version} {path}"
 
     return package.full_pretty_version
 
 
 def paths_csv(paths: List[Path]) -> str:
-    return ", ".join(f'"{str(c)}"' for c in paths)
+    return ", ".join(f'"{c!s}"' for c in paths)
 
 
 def is_dir_writable(path: Path, create: bool = False) -> bool:
@@ -135,3 +133,9 @@ def is_dir_writable(path: Path, create: bool = False) -> bool:
         return False
     else:
         return True
+
+
+def pluralize(count: int, word: str = "") -> str:
+    if count == 1:
+        return word
+    return word + "s"

src/poetry/utils/password_manager.py

@@ -61,9 +61,7 @@ class KeyRing:
             keyring.set_password(name, username, password)
         except (RuntimeError, keyring.errors.KeyringError) as e:
             raise KeyRingError(
-                "Unable to store the password for {} in the key ring: {}".format(
-                    name, str(e)
-                )
+                f"Unable to store the password for {name} in the key ring: {e}"
             )
 
     def delete_password(self, name: str, username: str) -> None:
@@ -89,7 +87,7 @@ class KeyRing:
         try:
             import keyring
         except Exception as e:
-            logger.debug(f"An error occurred while importing keyring: {str(e)}")
+            logger.debug(f"An error occurred while importing keyring: {e!s}")
             self._is_available = False
 
             return

src/poetry/utils/setup_reader.py

@@ -41,9 +41,8 @@ class SetupReader:
             if not filepath.exists():
                 continue
 
-            new_result = getattr(cls(), "read_{}".format(filename.replace(".", "_")))(
-                filepath
-            )
+            read_file_func = getattr(cls(), "read_" + filename.replace(".", "_"))
+            new_result = read_file_func(filepath)
 
             for key in result.keys():
                 if new_result[key]:

tests/conftest.py

@@ -309,7 +309,7 @@ def current_python(current_env: SystemEnv) -> Tuple[int, int, int]:
 
 @pytest.fixture(scope="session")
 def default_python(current_python: Tuple[int, int, int]) -> str:
-    return "^{}".format(".".join(str(v) for v in current_python[:2]))
+    return "^" + ".".join(str(v) for v in current_python[:2])
 
 
 @pytest.fixture

tests/console/commands/env/test_info.py

@@ -33,27 +33,21 @@ def tester(command_tester_factory: "CommandTesterFactory") -> "CommandTester":
 def test_env_info_displays_complete_info(tester: "CommandTester"):
     tester.execute()
 
-    expected = """
+    expected = f"""
 Virtualenv
 Python:         3.7.0
 Implementation: CPython
-Path:           {prefix}
-Executable:     {executable}
+Path:           {Path('/prefix')}
+Executable:     {sys.executable}
 Valid:          True
 
 System
 Platform:   darwin
 OS:         posix
-Python:     {base_version}
-Path:       {base_prefix}
-Executable: {base_executable}
-""".format(
-        prefix=str(Path("/prefix")),
-        base_prefix=str(Path("/base/prefix")),
-        base_version=".".join(str(v) for v in sys.version_info[:3]),
-        executable=sys.executable,
-        base_executable="python",
-    )
+Python:     {'.'.join(str(v) for v in sys.version_info[:3])}
+Path:       {Path('/base/prefix')}
+Executable: python
+"""
 
     assert expected == tester.io.fetch_output()
 

tests/console/commands/env/test_use.py

@@ -82,14 +82,10 @@ def test_activate_activates_non_existing_virtualenv_no_envs_file(
     assert envs[venv_name]["minor"] == "3.7"
     assert envs[venv_name]["patch"] == "3.7.1"
 
-    expected = """\
-Creating virtualenv {} in {}
-Using virtualenv: {}
-""".format(
-        venv_py37.name,
-        venv_py37.parent,
-        venv_py37,
-    )
+    expected = f"""\
+Creating virtualenv {venv_py37.name} in {venv_py37.parent}
+Using virtualenv: {venv_py37}
+"""
 
     assert expected == tester.io.fetch_output()
 
@@ -115,11 +111,9 @@ def test_get_prefers_explicitly_activated_virtualenvs_over_env_var(
 
     tester.execute(python_minor)
 
-    expected = """\
-Using virtualenv: {}
-""".format(
-        venv_dir
-    )
+    expected = f"""\
+Using virtualenv: {venv_dir}
+"""
 
     assert expected == tester.io.fetch_output()
 
@@ -151,13 +145,9 @@ def test_get_prefers_explicitly_activated_non_existing_virtualenvs_over_env_var(
 
     tester.execute(python_minor)
 
-    expected = """\
-Creating virtualenv {} in {}
-Using virtualenv: {}
-""".format(
-        venv_dir.name,
-        venv_dir.parent,
-        venv_dir,
-    )
+    expected = f"""\
+Creating virtualenv {venv_dir.name} in {venv_dir.parent}
+Using virtualenv: {venv_dir}
+"""
 
     assert expected == tester.io.fetch_output()

tests/console/commands/self/test_update.py

@@ -70,7 +70,7 @@ def test_self_update_can_update_from_recommended_installation(
 
     tester.execute()
 
-    expected_output = """\
+    expected_output = f"""\
 Updating Poetry to 1.2.0
 
 Updating dependencies
@@ -79,14 +79,12 @@ Resolving dependencies...
 Package operations: 0 installs, 2 updates, 0 removals
 
   - Updating cleo (0.8.2 -> 1.0.0)
-  - Updating poetry ({} -> {})
+  - Updating poetry ({__version__} -> {new_version})
 
 Updating the poetry script
 
-Poetry ({}) is installed now. Great!
-""".format(
-        __version__, new_version, new_version
-    )
+Poetry ({new_version}) is installed now. Great!
+"""
 
     assert tester.io.fetch_output() == expected_output
 

tests/console/commands/test_add.py

@@ -366,7 +366,7 @@ def test_add_directory_constraint(
     path = "../git/github.com/demo/demo"
     tester.execute(f"{path}" if not editable else f"-e {path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -376,10 +376,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (1.4.4)
-  • Installing demo (0.1.2 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  • Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == tester.io.fetch_output()
     assert tester.command.installer.executor.installations_count == 2
@@ -409,7 +407,7 @@ def test_add_directory_with_poetry(
     path = "../git/github.com/demo/pyproject-demo"
     tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -419,10 +417,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (1.4.4)
-  • Installing demo (0.1.2 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  • Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == tester.io.fetch_output()
     assert tester.command.installer.executor.installations_count == 2
@@ -443,7 +439,7 @@ def test_add_file_constraint_wheel(
     path = "../distributions/demo-0.1.0-py2.py3-none-any.whl"
     tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -453,10 +449,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (1.4.4)
-  • Installing demo (0.1.0 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  • Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == tester.io.fetch_output()
     assert tester.command.installer.executor.installations_count == 2
@@ -483,7 +477,7 @@ def test_add_file_constraint_sdist(
     path = "../distributions/demo-0.1.0.tar.gz"
     tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -493,10 +487,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (1.4.4)
-  • Installing demo (0.1.0 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  • Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == tester.io.fetch_output()
     assert tester.command.installer.executor.installations_count == 2
@@ -1305,7 +1297,7 @@ def test_add_directory_constraint_old_installer(
     path = "../git/github.com/demo/demo"
     old_tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -1315,10 +1307,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   - Installing pendulum (1.4.4)
-  - Installing demo (0.1.2 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  - Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == old_tester.io.fetch_output()
 
@@ -1345,7 +1335,7 @@ def test_add_directory_with_poetry_old_installer(
     path = "../git/github.com/demo/pyproject-demo"
     old_tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -1355,10 +1345,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   - Installing pendulum (1.4.4)
-  - Installing demo (0.1.2 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  - Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == old_tester.io.fetch_output()
 
@@ -1380,7 +1368,7 @@ def test_add_file_constraint_wheel_old_installer(
     path = "../distributions/demo-0.1.0-py2.py3-none-any.whl"
     old_tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -1390,10 +1378,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   - Installing pendulum (1.4.4)
-  - Installing demo (0.1.0 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  - Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == old_tester.io.fetch_output()
 
@@ -1422,7 +1408,7 @@ def test_add_file_constraint_sdist_old_installer(
     path = "../distributions/demo-0.1.0.tar.gz"
     old_tester.execute(f"{path}")
 
-    expected = """\
+    expected = f"""\
 
 Updating dependencies
 Resolving dependencies...
@@ -1432,10 +1418,8 @@ Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
 
   - Installing pendulum (1.4.4)
-  - Installing demo (0.1.0 {})
-""".format(
-        app.poetry.file.parent.joinpath(path).resolve().as_posix()
-    )
+  - Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+"""
 
     assert expected == old_tester.io.fetch_output()
 

tests/console/commands/test_cache.py

@@ -53,12 +53,10 @@ def test_cache_list(
 ):
     tester.execute()
 
-    expected = """\
-{}
-{}
-""".format(
-        repository_one, repository_two
-    )
+    expected = f"""\
+{repository_one}
+{repository_two}
+"""
 
     assert expected == tester.io.fetch_output()
 

tests/console/commands/test_config.py

@@ -45,7 +45,9 @@ def test_list_displays_default_value_if_not_set(
 ):
     tester.execute("--list")
 
-    expected = """cache-dir = {cache}
+    cache_dir = json.dumps(str(config_cache_dir))
+    venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
+    expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
 installer.max-workers = null
 installer.parallel = true
@@ -53,12 +55,8 @@ virtualenvs.create = true
 virtualenvs.in-project = null
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
-virtualenvs.path = {path}  # {virtualenvs}
-""".format(
-        cache=json.dumps(str(config_cache_dir)),
-        path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")),
-        virtualenvs=str(config_cache_dir / "virtualenvs"),
-    )
+virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+"""
 
     assert expected == tester.io.fetch_output()
 
@@ -70,7 +68,9 @@ def test_list_displays_set_get_setting(
 
     tester.execute("--list")
 
-    expected = """cache-dir = {cache}
+    cache_dir = json.dumps(str(config_cache_dir))
+    venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
+    expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
 installer.max-workers = null
 installer.parallel = true
@@ -78,12 +78,8 @@ virtualenvs.create = false
 virtualenvs.in-project = null
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
-virtualenvs.path = {path}  # {virtualenvs}
-""".format(
-        cache=json.dumps(str(config_cache_dir)),
-        path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")),
-        virtualenvs=str(config_cache_dir / "virtualenvs"),
-    )
+virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+"""
 
     assert config.set_config_source.call_count == 0
     assert expected == tester.io.fetch_output()
@@ -119,7 +115,9 @@ def test_list_displays_set_get_local_setting(
 
     tester.execute("--list")
 
-    expected = """cache-dir = {cache}
+    cache_dir = json.dumps(str(config_cache_dir))
+    venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
+    expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
 installer.max-workers = null
 installer.parallel = true
@@ -127,12 +125,8 @@ virtualenvs.create = false
 virtualenvs.in-project = null
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
-virtualenvs.path = {path}  # {virtualenvs}
-""".format(
-        cache=json.dumps(str(config_cache_dir)),
-        path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")),
-        virtualenvs=str(config_cache_dir / "virtualenvs"),
-    )
+virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+"""
 
     assert config.set_config_source.call_count == 1
     assert expected == tester.io.fetch_output()

tests/console/commands/test_init.py

@@ -180,7 +180,8 @@ def test_empty_license(tester: CommandTester):
     ]
     tester.execute(inputs="\n".join(inputs))
 
-    expected = """\
+    python = ".".join(str(c) for c in sys.version_info[:2])
+    expected = f"""\
 [tool.poetry]
 name = "my-package"
 version = "1.2.3"
@@ -191,9 +192,7 @@ packages = [{{include = "my_package"}}]
 
 [tool.poetry.dependencies]
 python = "^{python}"
-""".format(
-        python=".".join(str(c) for c in sys.version_info[:2])
-    )
+"""
     assert expected in tester.io.fetch_output()
 
 

tests/helpers.py

@@ -216,8 +216,6 @@ class TestRepository(Repository):
     def find_links_for_package(self, package: Package) -> List[Link]:
         return [
             Link(
-                "https://foo.bar/files/{}-{}-py2.py3-none-any.whl".format(
-                    escape_name(package.name), escape_version(package.version.text)
-                )
+                f"https://foo.bar/files/{escape_name(package.name)}-{escape_version(package.version.text)}-py2.py3-none-any.whl"
             )
         ]

tests/installation/test_chef.py

@@ -83,9 +83,7 @@ def test_get_cache_directory_for_link(config: "Config", config_cache_dir: Path):
     )
 
     expected = Path(
-        "{}/artifacts/ba/63/13/283a3b3b7f95f05e9e6f84182d276f7bb0951d5b0cc24422b33f7a4648".format(
-            config_cache_dir.as_posix()
-        )
+        f"{config_cache_dir.as_posix()}/artifacts/ba/63/13/283a3b3b7f95f05e9e6f84182d276f7bb0951d5b0cc24422b33f7a4648"
     )
 
     assert expected == directory

tests/installation/test_executor.py

@@ -161,18 +161,16 @@ def test_execute_executes_a_batch_of_operations(
         ]
     )
 
-    expected = """
+    expected = f"""
 Package operations: 4 installs, 1 update, 1 removal
 
   • Installing pytest (3.5.2)
   • Removing attrs (17.4.0)
   • Updating requests (2.18.3 -> 2.18.4)
-  • Installing demo (0.1.0 {})
-  • Installing simple-project (1.2.3 {})
+  • Installing demo (0.1.0 {file_package.source_url})
+  • Installing simple-project (1.2.3 {directory_package.source_url})
   • Installing demo (0.1.0 master)
-""".format(
-        file_package.source_url, directory_package.source_url
-    )
+"""
 
     expected = set(expected.splitlines())
     output = set(io.fetch_output().splitlines())

tests/masonry/builders/test_editable_builder.py

@@ -152,42 +152,36 @@ My Package
     assert str(dist_info.joinpath("entry_points.txt")) in records
     assert str(dist_info.joinpath("RECORD")) in records
 
-    baz_script = """\
-#!{python}
+    baz_script = f"""\
+#!{tmp_venv.python}
 import sys
 from bar import baz
 
 if __name__ == '__main__':
     sys.exit(baz.boom.bim())
-""".format(
-        python=tmp_venv.python
-    )
+"""
 
     assert baz_script == tmp_venv._bin_dir.joinpath("baz").read_text()
 
-    foo_script = """\
-#!{python}
+    foo_script = f"""\
+#!{tmp_venv.python}
 import sys
 from foo import bar
 
 if __name__ == '__main__':
     sys.exit(bar())
-""".format(
-        python=tmp_venv.python
-    )
+"""
 
     assert foo_script == tmp_venv._bin_dir.joinpath("foo").read_text()
 
-    fox_script = """\
-#!{python}
+    fox_script = f"""\
+#!{tmp_venv.python}
 import sys
 from fuz.foo import bar
 
 if __name__ == '__main__':
     sys.exit(bar.baz())
-""".format(
-        python=tmp_venv.python
-    )
+"""
 
     assert fox_script == tmp_venv._bin_dir.joinpath("fox").read_text()
 

tests/packages/test_locker.py

@@ -430,18 +430,15 @@ A = []
 def test_locker_should_emit_warnings_if_lock_version_is_newer_but_allowed(
     locker: Locker, caplog: "LogCaptureFixture"
 ):
-    content = """\
+    version = ".".join(Version.parse(Locker._VERSION).next_minor().text.split(".")[:2])
+    content = f"""\
 [metadata]
 lock-version = "{version}"
 python-versions = "~2.7 || ^3.4"
 content-hash = "c3d07fca33fba542ef2b2a4d75bf5b48d892d21a830e2ad9c952ba5123a52f77"
 
 [metadata.files]
-""".format(
-        version=".".join(
-            Version.parse(Locker._VERSION).next_minor().text.split(".")[:2]
-        )
-    )
+"""
     caplog.set_level(logging.WARNING, logger="poetry.packages.locker")
 
     locker.lock.write(tomlkit.parse(content))
@@ -524,16 +521,14 @@ def test_locker_should_neither_emit_warnings_nor_raise_error_for_lower_compatibl
     older_version = ".".join(
         [str(current_version.major), str(current_version.minor - 1)]
     )
-    content = """\
+    content = f"""\
 [metadata]
-lock-version = "{version}"
+lock-version = "{older_version}"
 python-versions = "~2.7 || ^3.4"
 content-hash = "c3d07fca33fba542ef2b2a4d75bf5b48d892d21a830e2ad9c952ba5123a52f77"
 
 [metadata.files]
-""".format(
-        version=older_version
-    )
+"""
     caplog.set_level(logging.WARNING, logger="poetry.packages.locker")
 
     locker.lock.write(tomlkit.parse(content))

tests/utils/test_authenticator.py

@@ -207,7 +207,7 @@ def test_authenticator_request_retries_on_exception(
     mocker: "MockerFixture", config: "Config", http: Type[httpretty.httpretty]
 ):
     sleep = mocker.patch("time.sleep")
-    sdist_uri = f"https://foo.bar/files/{str(uuid.uuid4())}/foo-0.1.0.tar.gz"
+    sdist_uri = f"https://foo.bar/files/{uuid.uuid4()!s}/foo-0.1.0.tar.gz"
     content = str(uuid.uuid4())
     seen = []
 
@@ -232,7 +232,7 @@ def test_authenticator_request_raises_exception_when_attempts_exhausted(
     mocker: "MockerFixture", config: "Config", http: Type[httpretty.httpretty]
 ):
     sleep = mocker.patch("time.sleep")
-    sdist_uri = f"https://foo.bar/files/{str(uuid.uuid4())}/foo-0.1.0.tar.gz"
+    sdist_uri = f"https://foo.bar/files/{uuid.uuid4()!s}/foo-0.1.0.tar.gz"
 
     def callback(*_: Any, **___: Any) -> None:
         raise requests.exceptions.ConnectionError(str(uuid.uuid4()))
@@ -267,7 +267,7 @@ def test_authenticator_request_retries_on_status_code(
     attempts: int,
 ):
     sleep = mocker.patch("time.sleep")
-    sdist_uri = f"https://foo.bar/files/{str(uuid.uuid4())}/foo-0.1.0.tar.gz"
+    sdist_uri = f"https://foo.bar/files/{uuid.uuid4()!s}/foo-0.1.0.tar.gz"
     content = str(uuid.uuid4())
 
     def callback(

tests/utils/test_env.py

@@ -470,10 +470,8 @@ def test_deactivate_non_activated_but_existing(
 
     venv_name = manager.generate_env_name("simple-project", str(poetry.file.parent))
 
-    (
-        Path(tmp_dir)
-        / "{}-py{}".format(venv_name, ".".join(str(c) for c in sys.version_info[:2]))
-    ).mkdir()
+    python = ".".join(str(c) for c in sys.version_info[:2])
+    (Path(tmp_dir) / f"{venv_name}-py{python}").mkdir()
 
     config.merge({"virtualenvs": {"path": str(tmp_dir)}})
 
@@ -485,9 +483,7 @@ def test_deactivate_non_activated_but_existing(
     manager.deactivate(NullIO())
     env = manager.get()
 
-    assert env.path == Path(tmp_dir) / "{}-py{}".format(
-        venv_name, ".".join(str(c) for c in sys.version_info[:2])
-    )
+    assert env.path == Path(tmp_dir) / f"{venv_name}-py{python}"
     assert Path("/prefix")
 
 
@@ -502,7 +498,7 @@ def test_deactivate_activated(
         del os.environ["VIRTUAL_ENV"]
 
     venv_name = manager.generate_env_name("simple-project", str(poetry.file.parent))
-    version = Version.parse(".".join(str(c) for c in sys.version_info[:3]))
+    version = Version.from_parts(*sys.version_info[:3])
     other_version = Version.parse("3.4") if version.major == 2 else version.next_minor()
     (Path(tmp_dir) / f"{venv_name}-py{version.major}.{version.minor}").mkdir()
     (
@@ -527,9 +523,7 @@ def test_deactivate_activated(
     manager.deactivate(NullIO())
     env = manager.get()
 
-    assert env.path == Path(tmp_dir) / "{}-py{}.{}".format(
-        venv_name, version.major, version.minor
-    )
+    assert env.path == Path(tmp_dir) / f"{venv_name}-py{version.major}.{version.minor}"
     assert Path("/prefix")
 
     envs = envs_file.read()
@@ -928,9 +922,9 @@ def test_create_venv_uses_patch_version_to_detect_compatibility(
     if "VIRTUAL_ENV" in os.environ:
         del os.environ["VIRTUAL_ENV"]
 
-    version = Version.parse(".".join(str(c) for c in sys.version_info[:3]))
-    poetry.package.python_versions = "^{}".format(
-        ".".join(str(c) for c in sys.version_info[:3])
+    version = Version.from_parts(*sys.version_info[:3])
+    poetry.package.python_versions = "^" + ".".join(
+        str(c) for c in sys.version_info[:3]
     )
     venv_name = manager.generate_env_name("simple-project", str(poetry.file.parent))
 
@@ -966,10 +960,8 @@ def test_create_venv_uses_patch_version_to_detect_compatibility_with_executable(
     if "VIRTUAL_ENV" in os.environ:
         del os.environ["VIRTUAL_ENV"]
 
-    version = Version.parse(".".join(str(c) for c in sys.version_info[:3]))
-    poetry.package.python_versions = "~{}".format(
-        ".".join(str(c) for c in (version.major, version.minor - 1, 0))
-    )
+    version = Version.from_parts(*sys.version_info[:3])
+    poetry.package.python_versions = f"~{version.major}.{version.minor-1}.0"
     venv_name = manager.generate_env_name("simple-project", str(poetry.file.parent))
 
     check_output = mocker.patch(
@@ -1087,16 +1079,10 @@ def test_env_finds_the_correct_executables(tmp_dir: str, manager: EnvManager):
     manager.build_venv(str(venv_path), with_pip=True)
     venv = VirtualEnv(venv_path)
 
-    default_executable = expected_executable = "python" + (".exe" if WINDOWS else "")
-    default_pip_executable = expected_pip_executable = "pip" + (
-        ".exe" if WINDOWS else ""
-    )
-    major_executable = "python{}{}".format(
-        sys.version_info[0], ".exe" if WINDOWS else ""
-    )
-    major_pip_executable = "pip{}{}".format(
-        sys.version_info[0], ".exe" if WINDOWS else ""
-    )
+    default_executable = expected_executable = f"python{'.exe' if WINDOWS else ''}"
+    default_pip_executable = expected_pip_executable = f"pip{'.exe' if WINDOWS else ''}"
+    major_executable = f"python{sys.version_info[0]}{'.exe' if WINDOWS else ''}"
+    major_pip_executable = f"pip{sys.version_info[0]}{'.exe' if WINDOWS else ''}"
 
     if (
         venv._bin_dir.joinpath(default_executable).exists()
@@ -1130,11 +1116,11 @@ def test_env_finds_the_correct_executables_for_generic_env(
     )
     venv = GenericEnv(parent_venv.path, child_env=VirtualEnv(child_venv_path))
 
-    expected_executable = "python{}.{}{}".format(
-        sys.version_info[0], sys.version_info[1], ".exe" if WINDOWS else ""
+    expected_executable = (
+        f"python{sys.version_info[0]}.{sys.version_info[1]}{'.exe' if WINDOWS else ''}"
     )
-    expected_pip_executable = "pip{}.{}{}".format(
-        sys.version_info[0], sys.version_info[1], ".exe" if WINDOWS else ""
+    expected_pip_executable = (
+        f"pip{sys.version_info[0]}.{sys.version_info[1]}{'.exe' if WINDOWS else ''}"
     )
 
     if WINDOWS:
@@ -1157,12 +1143,10 @@ def test_env_finds_fallback_executables_for_generic_env(
     )
     venv = GenericEnv(parent_venv.path, child_env=VirtualEnv(child_venv_path))
 
-    default_executable = "python" + (".exe" if WINDOWS else "")
-    major_executable = "python{}{}".format(
-        sys.version_info[0], ".exe" if WINDOWS else ""
-    )
-    minor_executable = "python{}.{}{}".format(
-        sys.version_info[0], sys.version_info[1], ".exe" if WINDOWS else ""
+    default_executable = f"python{'.exe' if WINDOWS else ''}"
+    major_executable = f"python{sys.version_info[0]}{'.exe' if WINDOWS else ''}"
+    minor_executable = (
+        f"python{sys.version_info[0]}.{sys.version_info[1]}{'.exe' if WINDOWS else ''}"
     )
     expected_executable = minor_executable
     if (
@@ -1179,12 +1163,10 @@ def test_env_finds_fallback_executables_for_generic_env(
         venv._bin_dir.joinpath(expected_executable).unlink()
         expected_executable = default_executable
 
-    default_pip_executable = "pip" + (".exe" if WINDOWS else "")
-    major_pip_executable = "pip{}{}".format(
-        sys.version_info[0], ".exe" if WINDOWS else ""
-    )
-    minor_pip_executable = "pip{}.{}{}".format(
-        sys.version_info[0], sys.version_info[1], ".exe" if WINDOWS else ""
+    default_pip_executable = f"pip{'.exe' if WINDOWS else ''}"
+    major_pip_executable = f"pip{sys.version_info[0]}{'.exe' if WINDOWS else ''}"
+    minor_pip_executable = (
+        f"pip{sys.version_info[0]}.{sys.version_info[1]}{'.exe' if WINDOWS else ''}"
     )
     expected_pip_executable = minor_pip_executable
     if (

tests/utils/test_exporter.py

@@ -1125,11 +1125,9 @@ def test_exporter_can_export_requirements_txt_with_directory_packages(
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    expected = """\
-foo @ {}/tests/fixtures/sample_project
-""".format(
-        working_directory.as_uri()
-    )
+    expected = f"""\
+foo @ {working_directory.as_uri()}/tests/fixtures/sample_project
+"""
 
     assert expected == content
 
@@ -1193,15 +1191,11 @@ def test_exporter_can_export_requirements_txt_with_nested_directory_packages(
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    expected = """\
-bar @ {}/tests/fixtures/project_with_nested_local/bar
-baz @ {}/tests/fixtures/project_with_nested_local
-foo @ {}/tests/fixtures/sample_project
-""".format(
-        working_directory.as_uri(),
-        working_directory.as_uri(),
-        working_directory.as_uri(),
-    )
+    expected = f"""\
+bar @ {working_directory.as_uri()}/tests/fixtures/project_with_nested_local/bar
+baz @ {working_directory.as_uri()}/tests/fixtures/project_with_nested_local
+foo @ {working_directory.as_uri()}/tests/fixtures/sample_project
+"""
 
     assert expected == content
 
@@ -1242,11 +1236,9 @@ def test_exporter_can_export_requirements_txt_with_directory_packages_and_marker
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    expected = """\
-foo @ {}/tests/fixtures/sample_project ; python_version < "3.7"
-""".format(
-        working_directory.as_uri()
-    )
+    expected = f"""\
+foo @ {working_directory.as_uri()}/tests/fixtures/sample_project ; python_version < "3.7"
+"""
 
     assert expected == content
 
@@ -1286,11 +1278,9 @@ def test_exporter_can_export_requirements_txt_with_file_packages(
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    expected = """\
-foo @ {}/tests/fixtures/distributions/demo-0.1.0.tar.gz
-""".format(
-        working_directory.as_uri()
-    )
+    expected = f"""\
+foo @ {working_directory.as_uri()}/tests/fixtures/distributions/demo-0.1.0.tar.gz
+"""
 
     assert expected == content
 
@@ -1331,11 +1321,9 @@ def test_exporter_can_export_requirements_txt_with_file_packages_and_markers(
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    expected = """\
-foo @ {}/tests/fixtures/distributions/demo-0.1.0.tar.gz ; python_version < "3.7"
-""".format(
-        working_directory.as_uri()
-    )
+    expected = f"""\
+foo @ {working_directory.as_uri()}/tests/fixtures/distributions/demo-0.1.0.tar.gz ; python_version < "3.7"
+"""
 
     assert expected == content
 
@@ -1570,7 +1558,7 @@ def test_exporter_exports_requirements_txt_with_dev_extras(
     with (Path(tmp_dir) / "requirements.txt").open(encoding="utf-8") as f:
         content = f.read()
 
-    assert content == "{}\n".format("\n".join(expected))
+    assert content == "\n".join(expected) + "\n"
 
 
 def test_exporter_exports_requirements_txt_with_legacy_packages_and_duplicate_sources(