Add setuptools command to generate setup.py

This change introduces `setuptools:setupfile` command that generates
a `setup.py` file for the project.

Resolves: python-poetry#761

poetry/console/application.py

@@ -31,6 +31,8 @@
 
 from .commands.self import SelfCommand
 
+from .commands.setuptools import SetupFileCommand
+
 from .config import ApplicationConfig
 
 from .commands.env import EnvCommand
@@ -94,6 +96,9 @@ def get_default_commands(self):  # type: () -> list
         # Env command
         commands += [EnvCommand()]
 
+        # Setuptools commands
+        commands += [SetupFileCommand()]
+
         # Self commands
         commands += [SelfCommand()]
 

poetry/console/commands/setuptools/__init__.py

@@ -0,0 +1 @@
+from .setupfile import SetupFileCommand

poetry/console/commands/setuptools/setupfile.py

@@ -0,0 +1,26 @@
+from poetry.console.commands.env_command import EnvCommand
+from poetry.io import NullIO
+from poetry.masonry.builders import SdistBuilder
+from poetry.utils._compat import Path
+from poetry.utils.env import NullEnv
+
+
+class SetupFileCommand(EnvCommand):
+    """
+    Generate a setuptools compatible <comment>setup.py</comment>
+
+    setuptools:setupfile
+    """
+
+    def handle(self):
+        try:
+            setupfile = Path(self.poetry.file.parent, "setup.py")
+            self.line("<info>Writing to <comment>{}</comment></info>".format(setupfile))
+            builder = SdistBuilder(self.poetry, NullEnv(), NullIO())
+            setupfile.write_bytes(builder.build_setup())
+        except Exception as e:
+            self.line("<error>{}</error>".format(e))
+            self.line("<error>Failed to write <comment>setup.py</comment>.</error>")
+            return 1
+
+        return 0

tests/console/commands/setuptools/test_setupfile.py

@@ -0,0 +1,36 @@
+import shutil
+import tempfile
+
+import pytest
+from cleo.testers import CommandTester
+
+from poetry.poetry import Poetry
+from poetry.utils._compat import Path
+from tests.test_poetry import fixtures_dir
+
+
+@pytest.fixture
+def tmp_dir():
+    dir_ = tempfile.mkdtemp(prefix="poetry_")
+    yield dir_
+    shutil.rmtree(dir_)
+
+
+@pytest.fixture
+def poetry(repo, tmp_dir):
+    project_dir = Path(tmp_dir, "sample_project")
+    shutil.copytree(str(fixtures_dir / "simple_project"), project_dir)
+    yield Poetry.create(project_dir)
+
+
+def test_setupfile(app):
+    command = app.find("setuptools:setupfile")
+    setupfile = Path(app.poetry.file.parent, "setup.py")
+
+    tester = CommandTester(command)
+    tester.execute([("command", command.get_name())])
+
+    assert setupfile.is_file()
+
+    expected = "Writing to {}\n".format(setupfile)
+    assert tester.get_display(True) == expected