GH-105793: Add follow_symlinks argument to pathlib.Path.is_dir()

Brings `pathlib.Path.is_dir()` in line with `os.DirEntry.is_dir()`, which will be important for implementing generic path walking and globbing.
python · barneygale · Jun 26, 2023 · Jun 14, 2023 · Jun 15, 2023 · Jun 15, 2023
commit 7c2c51adab68448ef1eba4118b669bbf9cbad483
@@ -953,14 +953,20 @@ call fails (for example because the path doesn't exist).
    if the file's gid isn't found in the system database.
 
 
-.. method:: Path.is_dir()
+.. method:: Path.is_dir(*, follow_symlinks=True)
 
-   Return ``True`` if the path points to a directory (or a symbolic link
-   pointing to a directory), ``False`` if it points to another kind of file.
+   Return ``True`` if the path points to a directory, ``False`` if it points
+   to another kind of file.
+
+   This method normally follows symlinks; to exclude symlinks to directories,
+   add the argument ``follow_symlinks=False``.
 
    ``False`` is also returned if the path doesn't exist or is a broken symlink;
    other errors (such as permission errors) are propagated.
 
+   .. versionchanged:: 3.13
+      The *follow_symlinks* parameter was added.
+
 
 .. method:: Path.is_file()
 

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
@@ -809,12 +809,12 @@ def exists(self, *, follow_symlinks=True):
             return False
         return True
 
-    def is_dir(self):
+    def is_dir(self, *, follow_symlinks=True):
         """
         Whether this path is a directory.
         """
         try:
-            return S_ISDIR(self.stat().st_mode)
+            return S_ISDIR(self.stat(follow_symlinks=follow_symlinks).st_mode)
         except OSError as e:
             if not _ignore_error(e):
                 raise

diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
@@ -2623,9 +2623,22 @@ def test_is_dir(self):
         if os_helper.can_symlink():
             self.assertFalse((P / 'linkA').is_dir())
             self.assertTrue((P / 'linkB').is_dir())
-            self.assertFalse((P/ 'brokenLink').is_dir(), False)
-        self.assertIs((P / 'dirA\udfff').is_dir(), False)
-        self.assertIs((P / 'dirA\x00').is_dir(), False)
+            self.assertFalse((P/ 'brokenLink').is_dir())
+        self.assertFalse((P / 'dirA\udfff').is_dir())
+        self.assertFalse((P / 'dirA\x00').is_dir())
+
+    def test_is_dir_no_follow_symlinks(self):
+        P = self.cls(BASE)
+        self.assertTrue((P / 'dirA').is_dir(follow_symlinks=False))
+        self.assertFalse((P / 'fileA').is_dir(follow_symlinks=False))
+        self.assertFalse((P / 'non-existing').is_dir(follow_symlinks=False))
+        self.assertFalse((P / 'fileA' / 'bah').is_dir(follow_symlinks=False))
+        if os_helper.can_symlink():
+            self.assertFalse((P / 'linkA').is_dir(follow_symlinks=False))
+            self.assertFalse((P / 'linkB').is_dir(follow_symlinks=False))
+            self.assertFalse((P/ 'brokenLink').is_dir(follow_symlinks=False))
+        self.assertFalse((P / 'dirA\udfff').is_dir(follow_symlinks=False))
+        self.assertFalse((P / 'dirA\x00').is_dir(follow_symlinks=False))
 
     def test_is_file(self):
         P = self.cls(BASE)

diff --git a/Misc/NEWS.d/next/Library/2023-06-14-18-41-18.gh-issue-105793.YSoykM.rst b/Misc/NEWS.d/next/Library/2023-06-14-18-41-18.gh-issue-105793.YSoykM.rst
@@ -0,0 +1,2 @@
+Add *follow_symlinks* keyword-only argument to :meth:`pathlib.Path.is_dir`,
+defaulting to ``True``.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Add follow_symlinks keyword-only argument to :meth:`pathlib.Path.is_dir`,
		defaulting to ``True``.