Add a pythonpath setting to allow paths to be added to sys.path. (#9134)

testing/test_pythonpath.py

@@ -0,0 +1,110 @@
+import sys
+from textwrap import dedent
+from typing import Generator
+from typing import List
+from typing import Optional
+
+import pytest
+from _pytest.pytester import Pytester
+
+
+@pytest.fixture()
+def file_structure(pytester: Pytester) -> None:
+    pytester.makepyfile(
+        test_foo="""
+        from foo import foo
+
+        def test_foo():
+            assert foo() == 1
+        """
+    )
+
+    pytester.makepyfile(
+        test_bar="""
+        from bar import bar
+
+        def test_bar():
+            assert bar() == 2
+        """
+    )
+
+    foo_py = pytester.mkdir("sub") / "foo.py"
+    content = dedent(
+        """
+        def foo():
+            return 1
+        """
+    )
+    foo_py.write_text(content, encoding="utf-8")
+
+    bar_py = pytester.mkdir("sub2") / "bar.py"
+    content = dedent(
+        """
+        def bar():
+            return 2
+        """
+    )
+    bar_py.write_text(content, encoding="utf-8")
+
+
+def test_one_dir(pytester: Pytester, file_structure) -> None:
+    pytester.makefile(".ini", pytest="[pytest]\npythonpath=sub\n")
+    result = pytester.runpytest("test_foo.py")
+    assert result.ret == 0
+    result.assert_outcomes(passed=1)
+
+
+def test_two_dirs(pytester: Pytester, file_structure) -> None:
+    pytester.makefile(".ini", pytest="[pytest]\npythonpath=sub sub2\n")
+    result = pytester.runpytest("test_foo.py", "test_bar.py")
+    assert result.ret == 0
+    result.assert_outcomes(passed=2)
+
+
+def test_module_not_found(pytester: Pytester, file_structure) -> None:
+    """Without the pythonpath setting, the module should not be found."""
+    pytester.makefile(".ini", pytest="[pytest]\n")
+    result = pytester.runpytest("test_foo.py")
+    assert result.ret == pytest.ExitCode.INTERRUPTED
+    result.assert_outcomes(errors=1)
+    expected_error = "E   ModuleNotFoundError: No module named 'foo'"
+    result.stdout.fnmatch_lines([expected_error])
+
+
+def test_no_ini(pytester: Pytester, file_structure) -> None:
+    """If no ini file, test should error."""
+    result = pytester.runpytest("test_foo.py")
+    assert result.ret == pytest.ExitCode.INTERRUPTED
+    result.assert_outcomes(errors=1)
+    expected_error = "E   ModuleNotFoundError: No module named 'foo'"
+    result.stdout.fnmatch_lines([expected_error])
+
+
+def test_clean_up(pytester: Pytester) -> None:
+    """Test that the pythonpath plugin cleans up after itself."""
+    # This is tough to test behaviorly because the cleanup really runs last.
+    # So the test make several implementation assumptions:
+    # - Cleanup is done in pytest_unconfigure().
+    # - Not a hookwrapper.
+    # So we can add a hookwrapper ourselves to test what it does.
+    pytester.makefile(".ini", pytest="[pytest]\npythonpath=I_SHALL_BE_REMOVED\n")
+    pytester.makepyfile(test_foo="""def test_foo(): pass""")
+
+    before: Optional[List[str]] = None
+    after: Optional[List[str]] = None
+
+    class Plugin:
+        @pytest.hookimpl(hookwrapper=True, tryfirst=True)
+        def pytest_unconfigure(self) -> Generator[None, None, None]:
+            nonlocal before, after
+            before = sys.path.copy()
+            yield
+            after = sys.path.copy()
+
+    result = pytester.runpytest_inprocess(plugins=[Plugin()])
+    assert result.ret == 0
+
+    assert before is not None
+    assert after is not None
+    assert any("I_SHALL_BE_REMOVED" in entry for entry in before)
+    assert not any("I_SHALL_BE_REMOVED" in entry for entry in after)