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

This addresses subst drive on Windows and symlinks on Linux.

Author: fabioz

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/acceptance_test.py

@@ -822,8 +822,8 @@ def test_cmdline_python_package_symlink(self, testdir, monkeypatch):
         if hasattr(py.path.local, "mksymlinkto"):
             result.stdout.fnmatch_lines(
                 [
-                    "lib/foo/bar/test_bar.py::test_bar PASSED*",
-                    "lib/foo/bar/test_bar.py::test_other PASSED*",
+                    "local/lib/foo/bar/test_bar.py::test_bar PASSED*",
+                    "local/lib/foo/bar/test_bar.py::test_other PASSED*",
                     "*2 passed*",
                 ]
             )

testing/test_collection.py

@@ -1171,13 +1171,13 @@ def test_collect_symlink_file_arg(testdir):
     real = testdir.makepyfile(
         real="""
         def test_nodeid(request):
-            assert request.node.nodeid == "real.py::test_nodeid"
+            assert request.node.nodeid == "symlink.py::test_nodeid"
         """
     )
     symlink = testdir.tmpdir.join("symlink.py")
     symlink.mksymlinkto(real)
     result = testdir.runpytest("-v", symlink)
-    result.stdout.fnmatch_lines(["real.py::test_nodeid PASSED*", "*1 passed in*"])
+    result.stdout.fnmatch_lines(["symlink.py::test_nodeid PASSED*", "*1 passed in*"])
     assert result.ret == 0
 
 

testing/test_conftest.py

@@ -195,7 +195,21 @@ def pytest_addoption(parser):
     reason="symlink not available on this platform",
 )
 def test_conftest_symlink(testdir):
-    """Ensure that conftest.py is used for resolved symlinks."""
+    """
+    Ensure that conftest.py is not found unless it's not a parent in the current
+    directory structure (i.e.: symlinks are not resolved).
+    """
+    # 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)
@@ -216,31 +230,16 @@ def fixture():
             ),
         }
     )
+
+    # 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"),

testing/test_link_resolve.py

@@ -0,0 +1,85 @@
+import os.path
+import subprocess
+import sys
+import textwrap
+from contextlib import contextmanager
+from string import ascii_lowercase
+
+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 = filename.dirpath()
+    basename = filename.basename
+
+    args = ["subst", drive, str(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 = filename.dirpath()
+    basename = filename.basename
+
+    target = directory / ".." / "sub2"
+    os.symlink(str(directory), str(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(str(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 "sub1/test_foo.py" not in stdout
+
+        # i.e.: Expect drive on windows because we just have drive:filename, whereas
+        # we expect a relative path on Linux.
+        expect = (
+            "*{}*".format(subst_p) if sys.platform == "win32" else "*sub2/test_foo.py*"
+        )
+        result.stdout.fnmatch_lines([expect])