Handle removal of vcs namespace package dependency gracefully

poetry/installation/pip_installer.py

@@ -105,12 +105,6 @@ def update(self, package, target):
         self.install(target, update=True)
 
     def remove(self, package):
-        # If we have a VCS package, remove its source directory
-        if package.source_type == "git":
-            src_dir = self._env.path / "src" / package.name
-            if src_dir.exists():
-                safe_rmtree(str(src_dir))
-
         try:
             self.run("uninstall", package.name, "-y")
         except CalledProcessError as e:
@@ -119,6 +113,17 @@ def remove(self, package):
 
             raise
 
+        # This is a workaround for https://github.com/pypa/pip/issues/4176
+        nspkg_pth_file = self._env.site_packages / "{}-nspkg.pth".format(package.name)
+        if nspkg_pth_file.exists():
+            nspkg_pth_file.unlink()
+
+        # If we have a VCS package, remove its source directory
+        if package.source_type == "git":
+            src_dir = self._env.path / "src" / package.name
+            if src_dir.exists():
+                safe_rmtree(str(src_dir))
+
     def run(self, *args, **kwargs):  # type: (...) -> str
         return self._env.run_pip(*args, **kwargs)
 

tests/conftest.py

@@ -11,6 +11,8 @@
 from poetry.config.config import Config as BaseConfig
 from poetry.config.dict_config_source import DictConfigSource
 from poetry.utils._compat import Path
+from poetry.utils.env import EnvManager
+from poetry.utils.env import VirtualEnv
 from tests.helpers import mock_clone
 from tests.helpers import mock_download
 
@@ -122,3 +124,15 @@ def tmp_dir():
     yield dir_
 
     shutil.rmtree(dir_)
+
+
+@pytest.fixture
+def tmp_venv(tmp_dir):
+    venv_path = Path(tmp_dir) / "venv"
+
+    EnvManager.build_venv(str(venv_path))
+
+    venv = VirtualEnv(venv_path)
+    yield venv
+
+    shutil.rmtree(str(venv.path))

tests/fixtures/git/github.com/demo/namespace-package-one/namespace_package/__init__.py

@@ -0,0 +1 @@
+__import__("pkg_resources").declare_namespace(__name__)

tests/fixtures/git/github.com/demo/namespace-package-one/namespace_package/one/__init__.py

@@ -0,0 +1 @@
+name = "one"

tests/fixtures/git/github.com/demo/namespace-package-one/setup.py

@@ -0,0 +1,15 @@
+from setuptools import setup, find_packages
+
+
+setup(
+    name="namespace_package_one",
+    version="1.0.0",
+    description="",
+    long_description="",
+    author="Python Poetry",
+    author_email="noreply@python-poetry.org",
+    license="MIT",
+    packages=find_packages(),
+    namespace_packages=["namespace_package"],
+    zip_safe=False,
+)

tests/installation/test_pip_installer.py

@@ -1,3 +1,5 @@
+import shutil
+
 import pytest
 
 from poetry.installation.pip_installer import PipInstaller
@@ -152,3 +154,42 @@ def test_requirement_git_develop_true(installer, package_git):
     expected = ["-e", "git+git@github.com:demo/demo.git@master#egg=demo"]
 
     assert expected == result
+
+
+def test_uninstall_git_package_nspkg_pth_cleanup(mocker, tmp_venv, pool):
+    # this test scenario requires a real installation using the pip installer
+    installer = PipInstaller(tmp_venv, NullIO(), pool)
+
+    # use a namepspace package
+    package = Package("namespace-package-one", "1.0.0")
+    package.source_type = "git"
+    package.source_url = "https://github.com/demo/namespace-package-one.git"
+    package.source_reference = "master"
+    package.develop = True
+
+    # we do this here because the virtual env might not be usable if failure case is triggered
+    pth_file_candidate = tmp_venv.site_packages / "{}-nspkg.pth".format(package.name)
+
+    # in order to reproduce the scenario where the git source is removed prior to proper
+    # clean up of nspkg.pth file, we need to make sure the fixture is copied and not
+    # symlinked into the git src directory
+    def copy_only(source, dest):
+        if dest.exists():
+            dest.unlink()
+
+        if source.is_dir():
+            shutil.copytree(str(source), str(dest))
+        else:
+            shutil.copyfile(str(source), str(dest))
+
+    mocker.patch("tests.helpers.copy_or_symlink", new=copy_only)
+
+    # install package and then remove it
+    installer.install(package)
+    installer.remove(package)
+
+    assert not Path(pth_file_candidate).exists()
+
+    # any command in the virtual environment should trigger the error message
+    output = tmp_venv.run("python", "-m", "site")
+    assert "Error processing line 1 of {}".format(pth_file_candidate) not in output

tests/utils/test_env.py

@@ -60,18 +60,6 @@ def manager(poetry):
     return EnvManager(poetry)
 
 
-@pytest.fixture
-def tmp_venv(tmp_dir, manager):
-    venv_path = Path(tmp_dir) / "venv"
-
-    manager.build_venv(str(venv_path))
-
-    venv = VirtualEnv(venv_path)
-    yield venv
-
-    shutil.rmtree(str(venv.path))
-
-
 def test_virtualenvs_with_spaces_in_their_path_work_as_expected(tmp_dir, manager):
     venv_path = Path(tmp_dir) / "Virtual Env"