Fix issue where working dir becomes wrong on subst drive on Windows. Fixes #5965 (#6523)

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

testing/test_conftest.py

@@ -7,6 +7,7 @@ import pytest
 from _pytest.config import ExitCode
 from _pytest.config import PytestPluginManager
 from _pytest.pathlib import Path
+from _pytest.pathlib import symlink_or_skip
 
 
 def ConftestWithSetinitial(path):
@@ -190,16 +191,25 @@ def test_conftest_confcutdir(testdir):
     result.stdout.no_fnmatch_line("*warning: could not load initial*")
 
 
-@pytest.mark.skipif(
-    not hasattr(py.path.local, "mksymlinkto"),
-    reason="symlink not available on this platform",
-)
 def test_conftest_symlink(testdir):
-    """Ensure that conftest.py is used for resolved symlinks."""
+    """
+    conftest.py discovery follows normal path resolution and does not resolve symlinks.
+    """
+    # Structure:
+    # /real
+    # /real/conftest.py
+    # /real/app
+    # /real/app/tests
+    # /real/app/tests/test_foo.py
+
+    # Links:
+    # /symlinktests -> /real/app/tests (running at symlinktests should fail)
+    # /symlink -> /real (running at /symlink should work)
+
     real = testdir.tmpdir.mkdir("real")
     realtests = real.mkdir("app").mkdir("tests")
-    testdir.tmpdir.join("symlinktests").mksymlinkto(realtests)
-    testdir.tmpdir.join("symlink").mksymlinkto(real)
+    symlink_or_skip(realtests, testdir.tmpdir.join("symlinktests"))
+    symlink_or_skip(real, testdir.tmpdir.join("symlink"))
     testdir.makepyfile(
         **{
             "real/app/tests/test_foo.py": "def test1(fixture): pass",
@@ -216,38 +226,20 @@ def test_conftest_symlink(testdir):
             ),
         }
     )
+
+    # Should fail because conftest cannot be found from the link structure.
     result = testdir.runpytest("-vs", "symlinktests")
-    result.stdout.fnmatch_lines(
-        [
-            "*conftest_loaded*",
-            "real/app/tests/test_foo.py::test1 fixture_used",
-            "PASSED",
-        ]
-    )
-    assert result.ret == ExitCode.OK
+    result.stdout.fnmatch_lines(["*fixture 'fixture' not found*"])
+    assert result.ret == ExitCode.TESTS_FAILED
 
     # Should not cause "ValueError: Plugin already registered" (#4174).
     result = testdir.runpytest("-vs", "symlink")
     assert result.ret == ExitCode.OK
 
-    realtests.ensure("__init__.py")
-    result = testdir.runpytest("-vs", "symlinktests/test_foo.py::test1")
-    result.stdout.fnmatch_lines(
-        [
-            "*conftest_loaded*",
-            "real/app/tests/test_foo.py::test1 fixture_used",
-            "PASSED",
-        ]
-    )
-    assert result.ret == ExitCode.OK
 
-
-@pytest.mark.skipif(
-    not hasattr(py.path.local, "mksymlinkto"),
-    reason="symlink not available on this platform",
-)
 def test_conftest_symlink_files(testdir):
-    """Check conftest.py loading when running in directory with symlinks."""
+    """Symlinked conftest.py are found when pytest is executed in a directory with symlinked
+    files."""
     real = testdir.tmpdir.mkdir("real")
     source = {
         "app/test_foo.py": "def test1(fixture): pass",
@@ -271,7 +263,7 @@ def test_conftest_symlink_files(testdir):
     build = testdir.tmpdir.mkdir("build")
     build.mkdir("app")
     for f in source:
-        build.join(f).mksymlinkto(real.join(f))
+        symlink_or_skip(real.join(f), build.join(f))
     build.chdir()
     result = testdir.runpytest("-vs", "app/test_foo.py")
     result.stdout.fnmatch_lines(["*conftest_loaded*", "PASSED"])