Only write lock file when installation is success (#7498)

(affects `poetry add` and `poetry update`)

Only write lock file when installation is success (#7498)
(affects `poetry add` and `poetry update`)
623bfffb · Wagner Macedo · GitHub · 161b19cb · 623bfffb · 623bfffb
Commit 623bfffb authored Apr 06, 2023 by Wagner Macedo Committed by GitHub Apr 06, 2023
8 changed files
--- a/src/poetry/installation/installer.py
+++ b/src/poetry/installation/installer.py
@@ -291,12 +291,10 @@ class Installer:
        lockfile_repo = LockfileRepository()
        self._populate_lockfile_repo(lockfile_repo, ops)
-        if self._update:
+        if self._lock and self._update:
+            # If we are only in lock mode, no need to go any further
            self._write_lock_file(lockfile_repo)
+            return 0
-            if self._lock:
-                # If we are only in lock mode, no need to go any further
-                return 0
        if self._groups is not None:
            root = self._package.with_dependency_groups(list(self._groups), only=True)
@@ -362,7 +360,13 @@ class Installer:
        self._filter_operations(ops, lockfile_repo)
        # Execute operations
-        return self._execute(ops)
+        status = self._execute(ops)
+        if status == 0 and self._update:
+            # Only write lock file when installation is success
+            self._write_lock_file(lockfile_repo)
+        return status
    def _write_lock_file(self, repo: LockfileRepository, force: bool = False) -> None:
        if self._write_lock and (force or self._update):

--- a/src/poetry/packages/locker.py
+++ b/src/poetry/packages/locker.py
@@ -224,6 +224,18 @@ class Locker:
        return repository
    def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
+        """Store lock data and eventually persist to the lock file"""
+        lock = self._compute_lock_data(root, packages)
+        if self._should_write(lock):
+            self._write_lock_data(lock)
+            return True
+        return False
+    def _compute_lock_data(
+        self, root: Package, packages: list[Package]
+    ) -> TOMLDocument:
        package_specs = self._lock_packages(packages)
        # Retrieving hashes
        for package in package_specs:
@@ -254,6 +266,10 @@ class Locker:
            "content-hash": self._content_hash,
        }
+        return lock
+    def _should_write(self, lock: TOMLDocument) -> bool:
+        # if lock file exists: compare with existing lock data
        do_write = True
        if self.is_locked():
            try:
@@ -263,8 +279,6 @@ class Locker:
                pass
            else:
                do_write = lock != lock_data
-        if do_write:
-            self._write_lock_data(lock)
        return do_write
    def _write_lock_data(self, data: TOMLDocument) -> None:

--- a/tests/console/commands/self/test_add_plugins.py
+++ b/tests/console/commands/self/test_add_plugins.py
@@ -49,11 +49,11 @@ Using version ^0.1.0 for poetry-plugin
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing poetry-plugin (0.1.0)
+Writing lock file
 """
    assert_plugin_add_result(tester, expected, "^0.1.0")
@@ -71,11 +71,11 @@ def test_add_with_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing poetry-plugin (0.2.0)
+Writing lock file
 """
    assert_plugin_add_result(tester, expected, "^0.2.0")
@@ -93,12 +93,12 @@ def test_add_with_git_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (2.0.5)
  • Installing poetry-plugin (0.1.2 9cf87a2)
+Writing lock file
 """
    assert_plugin_add_result(
@@ -119,13 +119,13 @@ def test_add_with_git_constraint_with_extras(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 3 installs, 0 updates, 0 removals
  • Installing pendulum (2.0.5)
  • Installing tomlkit (0.7.0)
  • Installing poetry-plugin (0.1.2 9cf87a2)
+Writing lock file
 """
    assert_plugin_add_result(
@@ -162,12 +162,12 @@ def test_add_with_git_constraint_with_subdirectory(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (2.0.5)
  • Installing poetry-plugin (0.1.2 9cf87a2)
+Writing lock file
 """
    constraint = {
@@ -262,11 +262,11 @@ Using version ^2.3.4 for poetry-plugin
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 0 installs, 1 update, 0 removals
  • Updating poetry-plugin (1.2.3 -> 2.3.4)
+Writing lock file
 """
    assert_plugin_add_result(tester, expected, "^2.3.4")
@@ -298,12 +298,12 @@ Using version ^1.2.3 for poetry-plugin
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 1 update, 0 removals
  • Updating tomlkit (0.7.1 -> 0.7.2)
  • Installing poetry-plugin (1.2.3)
+Writing lock file
 """
    assert_plugin_add_result(tester, expected, "^1.2.3")
--- a/tests/console/commands/self/test_remove_plugins.py
+++ b/tests/console/commands/self/test_remove_plugins.py
@@ -73,11 +73,11 @@ def test_remove_installed_package(tester: CommandTester):
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 0 installs, 0 updates, 1 removal
  • Removing poetry-plugin (1.2.3)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected

--- a/tests/console/commands/self/test_update.py
+++ b/tests/console/commands/self/test_update.py
@@ -71,12 +71,12 @@ Using version ^{new_version} for poetry
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 0 installs, 2 updates, 0 removals
  • Updating cleo (0.8.2 -> 1.0.0)
  • Updating poetry ({__version__} -> {new_version})
+Writing lock file
 """
    assert tester.io.fetch_output() == expected_output
--- a/tests/console/commands/test_add.py
+++ b/tests/console/commands/test_add.py
@@ -16,6 +16,8 @@ from tests.helpers import get_package
 if TYPE_CHECKING:
+    from typing import Any
    from cleo.testers.command_tester import CommandTester
    from pytest_mock import MockerFixture
@@ -70,11 +72,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -100,11 +102,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
    assert tester.command.installer.executor.installations_count == 1
@@ -119,11 +121,11 @@ Package operations: 1 install, 0 updates, 0 removals
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.1.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -167,11 +169,11 @@ def test_add_equal_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.1.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -191,11 +193,11 @@ def test_add_greater_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -225,12 +227,12 @@ def test_add_constraint_with_extras(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing msgpack-python (0.5.3)
  • Installing cachy (0.1.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -255,12 +257,12 @@ def test_add_constraint_dependencies(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing msgpack-python (0.5.3)
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -285,12 +287,12 @@ def test_add_git_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -321,12 +323,12 @@ def test_add_git_constraint_with_poetry(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -354,14 +356,14 @@ def test_add_git_constraint_with_extras(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 4 installs, 0 updates, 0 removals
  • Installing cleo (0.6.5)
  • Installing pendulum (1.4.4)
  • Installing tomlkit (0.5.5)
  • Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert tester.io.fetch_output().strip() == expected.strip()
@@ -400,11 +402,11 @@ def test_add_git_constraint_with_subdirectory(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing two (2.0.0 9cf87a2)
+Writing lock file
 """
    assert tester.io.fetch_output().strip() == expected.strip()
    assert tester.command.installer.executor.installations_count == 1
@@ -444,12 +446,12 @@ def test_add_git_ssh_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -491,12 +493,12 @@ def test_add_directory_constraint(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -532,12 +534,12 @@ def test_add_directory_with_poetry(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -564,12 +566,12 @@ def test_add_file_constraint_wheel(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -600,12 +602,12 @@ def test_add_file_constraint_sdist(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -640,12 +642,12 @@ def test_add_constraint_with_extras_option(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing msgpack-python (0.5.3)
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -680,13 +682,13 @@ def test_add_url_constraint_wheel(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  • Installing pendulum (1.4.4)
  • Installing demo\
 (0.1.0 https://python-poetry.org/distributions/demo-0.1.0-py2.py3-none-any.whl)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -722,8 +724,6 @@ def test_add_url_constraint_wheel_with_extras(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 4 installs, 0 updates, 0 removals
  • Installing cleo (0.6.5)
@@ -731,6 +731,8 @@ Package operations: 4 installs, 0 updates, 0 removals
  • Installing tomlkit (0.5.5)
  • Installing demo\
 (0.1.0 https://python-poetry.org/distributions/demo-0.1.0-py2.py3-none-any.whl)
+Writing lock file
 """
    # Order might be different, split into lines and compare the overall output.
    expected = set(expected.splitlines())
@@ -764,11 +766,11 @@ def test_add_constraint_with_python(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -802,11 +804,11 @@ def test_add_constraint_with_platform(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -853,11 +855,11 @@ def test_add_constraint_with_source(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -915,11 +917,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -962,11 +964,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing cachy (0.2.0)
+Writing lock file
 """
    assert tester.io.fetch_error() == warning
@@ -993,11 +995,11 @@ Using version ^3.13 for pyyaml
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing pyyaml (3.13)
+Writing lock file
 """
    assert tester.io.fetch_output() == expected
@@ -1112,11 +1114,11 @@ Using version ^1.1.2 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing foo (1.1.2)
+Writing lock file
 """
    assert expected in tester.io.fetch_output()
@@ -1141,11 +1143,11 @@ Using version ^1.2.3b1 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing foo (1.2.3b1)
+Writing lock file
 """
    assert expected in tester.io.fetch_output()
@@ -1164,11 +1166,11 @@ Using version ^1.2.3 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  • Installing foo (1.2.3)
+Writing lock file
 """
    assert expected in tester.io.fetch_output()
@@ -1212,11 +1214,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1245,11 +1247,11 @@ def test_add_equal_constraint_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.1.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1273,11 +1275,11 @@ def test_add_greater_constraint_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1309,12 +1311,12 @@ def test_add_constraint_with_extras_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing msgpack-python (0.5.3)
  - Installing cachy (0.1.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1343,12 +1345,12 @@ def test_add_constraint_dependencies_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing msgpack-python (0.5.3)
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1372,12 +1374,12 @@ def test_add_git_constraint_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1407,12 +1409,12 @@ def test_add_git_constraint_with_poetry_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1439,14 +1441,14 @@ def test_add_git_constraint_with_extras_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 4 installs, 0 updates, 0 removals
  - Installing cleo (0.6.5)
  - Installing pendulum (1.4.4)
  - Installing tomlkit (0.5.5)
  - Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1478,12 +1480,12 @@ def test_add_git_ssh_constraint_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.2 9cf87a2)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1520,12 +1522,12 @@ def test_add_directory_constraint_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1558,12 +1560,12 @@ def test_add_directory_with_poetry_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.2 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1591,12 +1593,12 @@ def test_add_file_constraint_wheel_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1629,12 +1631,12 @@ def test_add_file_constraint_sdist_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo (0.1.0 {app.poetry.file.parent.joinpath(path).resolve().as_posix()})
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1671,12 +1673,12 @@ def test_add_constraint_with_extras_option_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing msgpack-python (0.5.3)
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1713,13 +1715,13 @@ def test_add_url_constraint_wheel_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 2 installs, 0 updates, 0 removals
  - Installing pendulum (1.4.4)
  - Installing demo\
 (0.1.0 https://python-poetry.org/distributions/demo-0.1.0-py2.py3-none-any.whl)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1756,8 +1758,6 @@ def test_add_url_constraint_wheel_with_extras_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 4 installs, 0 updates, 0 removals
  - Installing cleo (0.6.5)
@@ -1765,6 +1765,8 @@ Package operations: 4 installs, 0 updates, 0 removals
  - Installing tomlkit (0.5.5)
  - Installing demo\
 (0.1.0 https://python-poetry.org/distributions/demo-0.1.0-py2.py3-none-any.whl)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1800,11 +1802,11 @@ def test_add_constraint_with_python_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1840,11 +1842,11 @@ def test_add_constraint_with_platform_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1893,11 +1895,11 @@ def test_add_constraint_with_source_old_installer(
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1959,11 +1961,11 @@ Using version ^0.2.0 for cachy
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing cachy (0.2.0)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -1993,11 +1995,11 @@ Using version ^3.13 for pyyaml
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing pyyaml (3.13)
+Writing lock file
 """
    assert old_tester.io.fetch_output() == expected
@@ -2058,11 +2060,11 @@ Using version ^1.1.2 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing foo (1.1.2)
+Writing lock file
 """
    assert expected in old_tester.io.fetch_output()
@@ -2090,11 +2092,11 @@ Using version ^1.2.3b1 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing foo (1.2.3b1)
+Writing lock file
 """
    assert expected in old_tester.io.fetch_output()
@@ -2116,11 +2118,11 @@ Using version ^1.2.3 for foo
 Updating dependencies
 Resolving dependencies...
-Writing lock file
 Package operations: 1 install, 0 updates, 0 removals
  - Installing foo (1.2.3)
+Writing lock file
 """
    assert expected in old_tester.io.fetch_output()
@@ -2157,7 +2159,8 @@ def test_add_keyboard_interrupt_restore_content(
    tester = command_tester_factory("add", poetry=poetry_with_up_to_date_lockfile)
    mocker.patch(
-        "poetry.installation.installer.Installer.run", side_effect=KeyboardInterrupt()
+        "poetry.installation.installer.Installer._execute",
+        side_effect=KeyboardInterrupt(),
    )
    original_pyproject_content = poetry_with_up_to_date_lockfile.file.read()
    original_lockfile_content = poetry_with_up_to_date_lockfile._locker.lock_data
@@ -2200,3 +2203,39 @@ def test_add_with_dry_run_keep_files_intact(
    assert (
        poetry_with_up_to_date_lockfile._locker.lock_data == original_lockfile_content
    )
+def test_add_should_not_change_lock_file_when_dependency_installation_fail(
+    poetry_with_up_to_date_lockfile: Poetry,
+    repo: TestRepository,
+    command_tester_factory: CommandTesterFactory,
+    mocker: MockerFixture,
+):
+    tester = command_tester_factory("add", poetry=poetry_with_up_to_date_lockfile)
+    repo.add_package(get_package("docker", "4.3.1"))
+    repo.add_package(get_package("cachy", "0.2.0"))
+    original_pyproject_content = poetry_with_up_to_date_lockfile.file.read()
+    original_lockfile_content = poetry_with_up_to_date_lockfile.locker.lock_data
+    def error(_: Any) -> int:
+        tester.io.write("\n  BuildError\n\n")
+        return 1
+    mocker.patch("poetry.installation.installer.Installer._execute", side_effect=error)
+    tester.execute("cachy")
+    expected = """\
+Using version ^0.2.0 for cachy
+Updating dependencies
+Resolving dependencies...
+  BuildError
+"""
+    assert poetry_with_up_to_date_lockfile.file.read() == original_pyproject_content
+    assert poetry_with_up_to_date_lockfile.locker.lock_data == original_lockfile_content
+    assert tester.io.fetch_output() == expected
--- a/tests/installation/test_installer.py
+++ b/tests/installation/test_installer.py
@@ -105,6 +105,7 @@ class Locker(BaseLocker):
        self._lock = lock_path / "poetry.lock"
        self._written_data = None
        self._locked = False
+        self._lock_data = None
        self._content_hash = self._get_content_hash()
    @property
@@ -2415,6 +2416,29 @@ def test_installer_can_handle_old_lock_files(
    assert installer.executor.installations_count == 8
+def test_installer_does_not_write_lock_file_when_installation_fails(
+    installer: Installer,
+    locker: Locker,
+    repo: Repository,
+    package: ProjectPackage,
+    mocker: MockerFixture,
+):
+    repo.add_package(get_package("A", "1.0"))
+    package.add_dependency(Factory.create_dependency("A", "~1.0"))
+    locker.locked(False)
+    mocker.patch("poetry.installation.installer.Installer._execute", return_value=1)
+    result = installer.run()
+    assert result == 1  # error
+    assert locker._lock_data is None
+    assert installer.executor.installations_count == 0
+    assert installer.executor.updates_count == 0
+    assert installer.executor.removals_count == 0
 @pytest.mark.parametrize("quiet", [True, False])
 def test_run_with_dependencies_quiet(
    installer: Installer,

--- a/tests/installation/test_installer_old.py
+++ b/tests/installation/test_installer_old.py
@@ -62,6 +62,7 @@ class Locker(BaseLocker):
        self._lock = lock_path / "poetry.lock"
        self._written_data = None
        self._locked = False
+        self._lock_data = None
        self._content_hash = self._get_content_hash()
    @property