Fix issue where working dir becomes wrong on symlinks. Fixes #5965

This addresses subst drive on Windows and symlinks on Linux.

changelog/5965.bugfix.rst

@@ -0,0 +1 @@
+No longer resolve symlinks so that the current directory remains correct with drives mapped with subst on Windows or symlinks on Linux.

src/_pytest/config/__init__.py

@@ -208,7 +208,7 @@ def get_config(args=None, plugins=None):
     config = Config(
         pluginmanager,
         invocation_params=Config.InvocationParams(
-            args=args or (), plugins=plugins, dir=Path().resolve()
+            args=args or (), plugins=plugins, dir=Path.cwd()
         ),
     )
 
@@ -462,7 +462,7 @@ def _getconftestmodules(self, path):
         # and allow users to opt into looking into the rootdir parent
         # directories instead of requiring to specify confcutdir
         clist = []
-        for parent in directory.realpath().parts():
+        for parent in directory.parts():
             if self._confcutdir and self._confcutdir.relto(parent):
                 continue
             conftestpath = parent.join("conftest.py")
@@ -771,7 +771,7 @@ def __init__(self, pluginmanager, *, invocation_params=None) -> None:
 
         if invocation_params is None:
             invocation_params = self.InvocationParams(
-                args=(), plugins=None, dir=Path().resolve()
+                args=(), plugins=None, dir=Path.cwd()
             )
 
         self.option = argparse.Namespace()

src/_pytest/fixtures.py

@@ -1288,7 +1288,7 @@ def getfixtureinfo(self, node, func, cls, funcargs=True):
     def pytest_plugin_registered(self, plugin):
         nodeid = None
         try:
-            p = py.path.local(plugin.__file__).realpath()
+            p = py.path.local(plugin.__file__)
         except AttributeError:
             pass
         else:

src/_pytest/main.py

@@ -642,7 +642,6 @@ def _parsearg(self, arg):
                     "file or package not found: " + arg + " (missing __init__.py?)"
                 )
             raise UsageError("file not found: " + arg)
-        fspath = fspath.realpath()
         return (fspath, parts)
 
     def matchnodes(self, matching, names):

testing/test_link_resolve.py

@@ -0,0 +1,78 @@
+from contextlib import contextmanager
+import os.path
+import subprocess
+from string import ascii_lowercase
+import sys
+import textwrap
+
+import py.path
+from _pytest import pytester
+
+
+@contextmanager
+def subst_path_windows(filename):
+    for c in ascii_lowercase[7:]:  # Create a subst drive from H-Z.
+        c += ":"
+        if not os.path.exists(c):
+            drive = c
+            break
+    else:
+        raise AssertionError("Unable to find suitable drive letter for subst.")
+
+    directory = os.path.dirname(filename)
+    basename = os.path.basename(filename)
+
+    args = ["subst", drive, directory]
+    subprocess.check_call(args)
+    assert os.path.exists(drive)
+    try:
+        filename = py.path.local(drive) / basename
+        yield filename
+    finally:
+        args = ["subst", "/D", drive]
+        subprocess.check_call(args)
+
+
+@contextmanager
+def subst_path_linux(filename):
+    directory = os.path.dirname(filename)
+    basename = os.path.basename(filename)
+
+    target = py.path.local(directory) / ".." / "sub2"
+    os.symlink(directory, target, target_is_directory=True)
+    try:
+        filename = target / basename
+        yield filename
+    finally:
+        # We don't need to unlink (it's all in the tempdir).
+        pass
+
+
+def test_link_resolve(testdir: pytester.Testdir) -> None:
+    """
+    See: https://github.com/pytest-dev/pytest/issues/5965
+    """
+    sub1 = testdir.mkpydir("sub1")
+    p = sub1.join("test_foo.py")
+    p.write(
+        textwrap.dedent(
+            """
+        import pytest
+        def test_foo():
+            raise AssertionError()
+        """
+        )
+    )
+
+    subst = subst_path_linux
+    if sys.platform == "win32":
+        subst = subst_path_windows
+
+    with subst(p) as subst_p:
+        result = testdir.runpytest(subst_p, "-v")
+        # i.e.: Make sure that the error is reported as a relative path, not as a
+        # resolved path.
+        # See: https://github.com/pytest-dev/pytest/issues/5965
+        stdout = result.stdout.str()
+        assert str(p) not in stdout
+        assert str(subst_p) in stdout