Fixed the behavior on Windows.

Author: aklajnert

src/_pytest/nodes.py

@@ -565,7 +565,7 @@ def _recurse(self, dirpath: py.path.local) -> bool:
             return False
 
         duplicate_paths = self.config.pluginmanager._duplicatepaths
-        realpath = dirpath.realpath()
+        realpath = _resolve_symlink(dirpath)
         if realpath in duplicate_paths:
             return False
         duplicate_paths.add(realpath)
@@ -600,7 +600,7 @@ def _collectfile(
             keepduplicates = self.config.getoption("keepduplicates")
             if not keepduplicates:
                 duplicate_paths = self.config.pluginmanager._duplicatepaths
-                resolved_path = path.realpath()
+                resolved_path = _resolve_symlink(path)
                 if resolved_path in duplicate_paths:
                     return ()
                 else:
@@ -670,3 +670,11 @@ def location(self) -> Tuple[str, Optional[int], str]:
         relfspath = self.session._node_location_to_relpath(fspath)
         assert type(location[2]) is str
         return (relfspath, location[1], location[2])
+
+
+def _resolve_symlink(local_path):
+    """
+    The `LocalPath.realpath()` works fine on Linux, but on Windows, the symlinks are not resolved.
+    This function makes sure that the symlink resolve is consistent.
+    """
+    return local_path.__class__(Path(local_path.strpath).resolve())

testing/test_collection.py

@@ -1285,7 +1285,7 @@ def test_collect_pkg_init_only(testdir):
 
 @pytest.mark.parametrize("use_pkg", (True, False))
 def test_collect_sub_with_symlinks(use_pkg, testdir):
-    """Symlinked files won't be resolved again."""
+    """Symlinked files won't be collected multiple times."""
     sub = testdir.mkdir("sub")
     if use_pkg:
         sub.ensure("__init__.py")