Support PEP-517 officially

docs/docs/pyproject.md

@@ -217,3 +217,22 @@ To match the example in the setuptools documentation, you would use the followin
 [tool.poetry.plugins."blogtool.parsers"]
 ".rst" = "some_module:SomeClass"
 ```
+
+## Poetry and PEP-517
+
+[PEP-517](https://www.python.org/dev/peps/pep-0517/) introduces a standard way
+to define alternative build systems to build a Python project.
+
+Poetry is compliant with PEP-517 so if you use Poetry to manage your Python
+project you should reference it in the `build-system` section of the `pyproject.toml`
+file like so:
+
+```toml
+[build-system]
+requires = ["poetry>=0.12"]
+build-backend = "poetry.masonry.api"
+```
+
+!!!note
+
+    When using the `new` or `init` command this section will be automatically added.

poetry/layouts/layout.py

 from tomlkit import dumps
 from tomlkit import loads
+from tomlkit import table
 
 from poetry.utils.helpers import module_name
 
@@ -37,6 +38,9 @@ license = ""
 [tool.poetry.dev-dependencies]
 """
 
+BUILD_SYSTEM_MIN_VERSION = "0.12"
+BUILD_SYSTEM_MAX_VERSION = None
+
 
 class Layout(object):
     def __init__(
@@ -102,6 +106,17 @@ class Layout(object):
         for dep_name, dep_constraint in self._dev_dependencies.items():
             poetry_content["dev-dependencies"][dep_name] = dep_constraint
 
+        # Add build system
+        build_system = table()
+        build_system_version = ">=" + BUILD_SYSTEM_MIN_VERSION
+        if BUILD_SYSTEM_MAX_VERSION is not None:
+            build_system_version += ",<" + BUILD_SYSTEM_MAX_VERSION
+
+        build_system.add("requires", ["poetry" + build_system_version])
+        build_system.add("build-backend", "poetry.masonry.api")
+
+        content.add("build-system", build_system)
+
         return dumps(content)
 
     def _create_default(self, path, src=True):

poetry/masonry/api.py

@@ -8,6 +8,7 @@ from pathlib import Path
 
 from poetry.poetry import Poetry
 from poetry.io import NullIO
+from poetry.utils._compat import unicode
 from poetry.utils.env import SystemEnv
 
 from .builders import SdistBuilder
@@ -15,17 +16,16 @@ from .builders import WheelBuilder
 
 log = logging.getLogger(__name__)
 
-# PEP 517 specifies that the CWD will always be the source tree
-poetry = Poetry.create(".")
-
 
 def get_requires_for_build_wheel(config_settings=None):
     """
     Returns a list of requirements for building, as strings
     """
-    main, extras = SdistBuilder.convert_dependencies(poetry.package.requires)
+    poetry = Poetry.create(".")
+
+    main, _ = SdistBuilder.convert_dependencies(poetry.package, poetry.package.requires)
 
-    return main + extras
+    return main
 
 
 # For now, we require all dependencies to build either a wheel or an sdist.
@@ -34,15 +34,21 @@ get_requires_for_build_sdist = get_requires_for_build_wheel
 
 def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
     """Builds a wheel, places it in wheel_directory"""
-    info = WheelBuilder.make_in(poetry, NullIO(), Path(wheel_directory))
+    poetry = Poetry.create(".")
 
-    return info.file.name
+    return unicode(
+        WheelBuilder.make_in(
+            poetry, SystemEnv(Path(sys.prefix)), NullIO(), Path(wheel_directory)
+        )
+    )
 
 
 def build_sdist(sdist_directory, config_settings=None):
     """Builds an sdist, places it in sdist_directory"""
-    path = SdistBuilder(poetry, SystemEnv(sys.prefix), NullIO()).build(
+    poetry = Poetry.create(".")
+
+    path = SdistBuilder(poetry, SystemEnv(Path(sys.prefix)), NullIO()).build(
         Path(sdist_directory)
     )
 
-    return path.name
+    return unicode(path.name)

poetry/masonry/builders/wheel.py

@@ -48,6 +48,8 @@ class WheelBuilder(Builder):
         wb = WheelBuilder(poetry, env, io, target_dir=directory, original=original)
         wb.build()
 
+        return wb.wheel_filename
+
     @classmethod
     def make(cls, poetry, env, io):
         """Build a wheel in the dist/ directory, and optionally upload it."""

tests/masonry/test_api.py

+import os
+import tarfile
+import zipfile
+
+from contextlib import contextmanager
+
+from poetry.masonry import api
+from poetry.utils.helpers import temporary_directory
+
+
+@contextmanager
+def cwd(directory):
+    prev = os.getcwd()
+    os.chdir(str(directory))
+    try:
+        yield
+    finally:
+        os.chdir(prev)
+
+
+fixtures = os.path.join(os.path.dirname(__file__), "builders", "fixtures")
+
+
+def test_get_requires_for_build_wheel():
+    expected = ["cleo>=0.6.0,<0.7.0", "cachy[msgpack]>=0.2.0,<0.3.0"]
+    with cwd(os.path.join(fixtures, "complete")):
+        api.get_requires_for_build_wheel() == expected
+
+
+def test_get_requires_for_build_sdist():
+    expected = ["cleo>=0.6.0,<0.7.0", "cachy[msgpack]>=0.2.0,<0.3.0"]
+    with cwd(os.path.join(fixtures, "complete")):
+        api.get_requires_for_build_sdist() == expected
+
+
+def test_build_wheel():
+    with temporary_directory() as tmp_dir, cwd(os.path.join(fixtures, "complete")):
+        filename = api.build_wheel(tmp_dir)
+
+        with zipfile.ZipFile(str(os.path.join(tmp_dir, filename))) as zip:
+            namelist = zip.namelist()
+
+            assert "my_package-1.2.3.dist-info/entry_points.txt" in namelist
+            assert "my_package-1.2.3.dist-info/WHEEL" in namelist
+            assert "my_package-1.2.3.dist-info/METADATA" in namelist
+
+
+def test_build_sdist():
+    with temporary_directory() as tmp_dir, cwd(os.path.join(fixtures, "complete")):
+        filename = api.build_sdist(tmp_dir)
+
+        with tarfile.open(str(os.path.join(tmp_dir, filename))) as tar:
+            namelist = tar.getnames()
+
+            assert "my-package-1.2.3/LICENSE" in namelist