Fix Windows drive-relative Path.resolve(strict=False)

CHANGES.md

@@ -13,6 +13,9 @@ The released versions correspond to PyPI releases.
 
 ### Fixes
 
+* fixed `Path.resolve(strict=False)` incorrectly resolving Windows
+  drive-relative paths against the drive root instead of the current directory
+  (see [#1324](https://github.com/pytest-dev/pyfakefs/issues/1324))
 * fixed a crash if the stack limit was set to a low value
   (see [#1313](https://github.com/pytest-dev/pyfakefs/issues/1313))
 * fixed `os.ftruncate` to inspect the `FakeFileWrapper` returned by

pyfakefs/fake_path.py

@@ -413,13 +413,22 @@ def _join_real_path(
         if self.filesystem.starts_with_root_path(rest):
             if self.filesystem.is_windows_fs:
                 drive, rest = self.filesystem.splitdrive(rest)
-                if not drive:
+                if drive and not self.filesystem.starts_with_sep(rest):
                     cwd = matching_string(path, self.filesystem.cwd)
-                    drive, _ = self.filesystem.splitdrive(cwd)
-                path = drive + sep
+                    cwd_drive, _ = self.filesystem.splitdrive(cwd)
+                    if drive.lower() == cwd_drive.lower():
+                        path = cwd
+                    else:
+                        path = drive + sep
+                else:
+                    if not drive:
+                        cwd = matching_string(path, self.filesystem.cwd)
+                        drive, _ = self.filesystem.splitdrive(cwd)
+                    path = drive + sep
+                    rest = rest[1:]
             else:
                 path = sep
-            rest = rest[1:]
+                rest = rest[1:]
 
         while rest:
             name, _, rest = rest.partition(sep)

pyfakefs/tests/fake_pathlib_test.py

@@ -657,6 +657,31 @@ def test_resolve(self):
             self.path(self.os.path.realpath(self.make_path("antoine", "setup.py"))),
         )
 
+    def test_resolve_drive_relative_path(self):
+        # Regression test for #1324: a drive prefix does not imply a root path.
+        self.check_windows_only()
+        cwd = self.make_path("test")
+        self.create_dir(cwd)
+        self.create_file(self.os.path.join(cwd, "test_data", "dummy1.xml"))
+        self.os.chdir(cwd)
+        expected = self.os.path.join(cwd, "test", "test_data", "dummy1.xml")
+        drive = self.path.cwd().drive
+        for prefix in (drive.lower(), drive.upper()):
+            path = self.path(f"{prefix}test\\test_data/dummy1.xml")
+            self.assert_equal_paths(path.resolve(strict=False), expected)
+
+    def test_resolve_drive_relative_existing_file(self):
+        self.check_windows_only()
+        cwd = self.make_path("test")
+        self.create_dir(cwd)
+        expected = self.os.path.join(cwd, "test_data", "dummy1.xml")
+        self.create_file(expected)
+        self.os.chdir(cwd)
+        drive = self.path.cwd().drive
+        for prefix in (drive.lower(), drive.upper()):
+            path = self.path(f"{prefix}test_data/dummy1.xml")
+            self.assert_equal_paths(path.resolve(strict=False), expected)
+
     def test_stat_file_in_unreadable_dir(self):
         self.check_posix_only()
         dir_path = self.make_path("some_dir")