Fix pytest with mixed up filename casing.

AUTHORS

@@ -55,6 +55,7 @@ Charnjit SiNGH (CCSJ)
 Chris Lamb
 Christian Boelsen
 Christian Fetzer
+Christian Neumüller
 Christian Theunert
 Christian Tismer
 Christopher Gilling

changelog/5792.bugfix.rst

@@ -0,0 +1,3 @@
+Windows: Fix error that occurs in certain circumstances when loading
+``conftest.py`` from a working directory that has casing other than the one stored
+in the filesystem (e.g., ``c:\test`` instead of ``C:\test``).

src/_pytest/config/__init__.py

@@ -30,6 +30,7 @@
 from _pytest.compat import importlib_metadata
 from _pytest.outcomes import fail
 from _pytest.outcomes import Skipped
+from _pytest.pathlib import unique_path
 from _pytest.warning_types import PytestConfigWarning
 
 hookimpl = HookimplMarker("pytest")
@@ -366,7 +367,7 @@ def _set_initial_conftests(self, namespace):
         """
         current = py.path.local()
         self._confcutdir = (
-            current.join(namespace.confcutdir, abs=True)
+            unique_path(current.join(namespace.confcutdir, abs=True))
             if namespace.confcutdir
             else None
         )
@@ -405,19 +406,18 @@ def _getconftestmodules(self, path):
         else:
             directory = path
 
+        directory = unique_path(directory)
+
         # XXX these days we may rather want to use config.rootdir
         # 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")
             if conftestpath.isfile():
-                # Use realpath to avoid loading the same conftest twice
-                # with build systems that create build directories containing
-                # symlinks to actual files.
-                mod = self._importconftest(conftestpath.realpath())
+                mod = self._importconftest(conftestpath)
                 clist.append(mod)
         self._dirpath2confmods[directory] = clist
         return clist
@@ -432,6 +432,10 @@ def _rget_with_confmod(self, name, path):
         raise KeyError(name)
 
     def _importconftest(self, conftestpath):
+        # Use realpath to avoid loading the same conftest twice
+        # with build systems that create build directories containing
+        # symlinks to actual files.
+        conftestpath = unique_path(conftestpath)
         try:
             return self._conftestpath2mod[conftestpath]
         except KeyError:

src/_pytest/pathlib.py

@@ -11,6 +11,7 @@
 from os.path import expanduser
 from os.path import expandvars
 from os.path import isabs
+from os.path import normcase
 from os.path import sep
 from posixpath import sep as posix_sep
 
@@ -334,3 +335,12 @@ def fnmatch_ex(pattern, path):
 def parts(s):
     parts = s.split(sep)
     return {sep.join(parts[: i + 1]) or sep for i in range(len(parts))}
+
+
+def unique_path(path):
+    """Returns a unique path in case-insensitive (but case-preserving) file
+    systems such as Windows.
+
+    This is needed only for ``py.path.local``; ``pathlib.Path`` handles this
+    natively with ``resolve()``."""
+    return type(path)(normcase(str(path.realpath())))

testing/test_conftest.py

@@ -1,10 +1,12 @@
+import os.path
 import textwrap
 
 import py
 
 import pytest
 from _pytest.config import PytestPluginManager
 from _pytest.main import ExitCode
+from _pytest.pathlib import unique_path
 
 
 def ConftestWithSetinitial(path):
@@ -141,11 +143,11 @@ def test_conftestcutdir(testdir):
     # but we can still import a conftest directly
     conftest._importconftest(conf)
     values = conftest._getconftestmodules(conf.dirpath())
-    assert values[0].__file__.startswith(str(conf))
+    assert values[0].__file__.startswith(str(unique_path(conf)))
     # and all sub paths get updated properly
     values = conftest._getconftestmodules(p)
     assert len(values) == 1
-    assert values[0].__file__.startswith(str(conf))
+    assert values[0].__file__.startswith(str(unique_path(conf)))
 
 
 def test_conftestcutdir_inplace_considered(testdir):
@@ -154,7 +156,7 @@ def test_conftestcutdir_inplace_considered(testdir):
     conftest_setinitial(conftest, [conf.dirpath()], confcutdir=conf.dirpath())
     values = conftest._getconftestmodules(conf.dirpath())
     assert len(values) == 1
-    assert values[0].__file__.startswith(str(conf))
+    assert values[0].__file__.startswith(str(unique_path(conf)))
 
 
 @pytest.mark.parametrize("name", "test tests whatever .dotdir".split())
@@ -164,7 +166,7 @@ def test_setinitial_conftest_subdirs(testdir, name):
     conftest = PytestPluginManager()
     conftest_setinitial(conftest, [sub.dirpath()], confcutdir=testdir.tmpdir)
     if name not in ("whatever", ".dotdir"):
-        assert subconftest in conftest._conftestpath2mod
+        assert unique_path(subconftest) in conftest._conftestpath2mod
         assert len(conftest._conftestpath2mod) == 1
     else:
         assert subconftest not in conftest._conftestpath2mod
@@ -275,6 +277,21 @@ def fixture():
     assert result.ret == ExitCode.OK
 
 
+@pytest.mark.skipif(
+    os.path.normcase("x") != os.path.normcase("X"),
+    reason="only relevant for case insensitive file systems",
+)
+def test_conftest_badcase(testdir):
+    """Check conftest.py loading when directory casing is wrong."""
+    testdir.tmpdir.mkdir("JenkinsRoot").mkdir("test")
+    source = {"setup.py": "", "test/__init__.py": "", "test/conftest.py": ""}
+    testdir.makepyfile(**{"JenkinsRoot/%s" % k: v for k, v in source.items()})
+
+    testdir.tmpdir.join("jenkinsroot/test").chdir()
+    result = testdir.runpytest()
+    assert result.ret == ExitCode.NO_TESTS_COLLECTED
+
+
 def test_no_conftest(testdir):
     testdir.makeconftest("assert 0")
     result = testdir.runpytest("--noconftest")