is_type_comment now checks for extra or zero spaces (psf#2097)

src/black/nodes.py

@@ -2,6 +2,7 @@
 blib2to3 Node/Leaf transformation-related utility functions.
 """
 
+import re
 import sys
 from typing import Final, Generic, Iterator, Literal, Optional, TypeVar, Union
 
@@ -911,7 +912,10 @@ def is_type_comment(leaf: Leaf) -> bool:
     used in modern version of Python, this function may be deprecated in the future."""
     t = leaf.type
     v = leaf.value
-    return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:")
+    return (
+        t in {token.COMMENT, STANDALONE_COMMENT}
+        and bool(re.match(r"#\s*type:", v))
+    )
 
 
 def is_type_ignore_comment(leaf: Leaf) -> bool:

tests/test_nodes.py

@@ -0,0 +1,28 @@
+"""Test the black.nodes module."""
+
+import pytest
+
+from black import Leaf, token
+from black.nodes import is_type_comment
+
+
+@pytest.mark.parametrize(
+    "comment_text, expected",
+    [
+        ("# type: int", True),
+        ("#type:int", True),
+        ("#   type:    str", True),
+        ("# type   :List[int]", False),
+        ("#    type   :    Dict[str, Any]", False),
+        ("#type :", False),
+        ("#type:   ", True),
+        ("#", False),
+        ("# some other comment type: ", False),
+        ("# type", False),
+        ("# type:", True),
+        ("#  type  :", False),
+    ],
+)
+def test_is_type_comment(comment_text: str, expected: bool) -> None:
+    leaf = Leaf(token.COMMENT, comment_text)
+    assert is_type_comment(leaf) == expected