test(api-core): add test case verifying UUID_REGEX strictness

Author: hebaalazzeh

packages/google-api-core/tests/unit/gapic/test_requests.py

@@ -113,3 +113,9 @@ def test_setup_request_id(request_obj, is_proto3_optional, expected):
         assert re.fullmatch(UUID_REGEX, value)
     else:
         assert value == expected
+
+
+def test_uuid_regex_rejects_trailing_garbage():
+    # Verify that UUID_REGEX with re.fullmatch rejects trailing characters
+    invalid_uuid = "12345678-1234-4123-8123-123456789012_extra"
+    assert re.fullmatch(UUID_REGEX, invalid_uuid) is None