Update tests/test_black.py

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

tests/test_black.py

@@ -2895,7 +2895,7 @@ def test_assert_equivalent_fstring(self) -> None:
             pytest.skip("relies on 3.12+ syntax")
         # https://github.com/psf/black/issues/4268
         self.check_ast_equivalence(
-            """print(f"{"|".join(['a','b','c'])}")""",
+            """print(f"{"|".join([a,b,c])}")""",
             """print(f"{" | ".join([a,b,c])}")""",
             should_fail=True,
         )