gh-153569: test nesting without parser recursion

Author: pablogsal

Lib/test/test_fstring.py

@@ -663,10 +663,7 @@ def create_nested_fstring(n):
             prev = create_nested_fstring(n-1)
             return f'f"{{{prev}}}"'
 
-        compile(create_nested_fstring(149), "<string>", "eval")
-        with self.assertRaisesRegex(
-                SyntaxError, "too many nested f-strings or t-strings"):
-            compile(create_nested_fstring(150), "<string>", "eval")
+        raises_syntax_or_memory_error(create_nested_fstring(160))
         raises_syntax_or_memory_error("f'{" + "("*100 + "}'")
         raises_syntax_or_memory_error("f'{" + "("*1000 + "}'")
         raises_syntax_or_memory_error("f'{" + "("*10_000 + "}'")

Lib/test/test_tokenize.py

@@ -2590,6 +2590,21 @@ def test_carriage_return_after_debug_comment(self):
                         ("unexpected EOF in multi-line statement", (1, 7)),
                     )
 
+    def test_formatted_string_nesting_limit(self):
+        def nested_string(depth, prefix):
+            source = "'x'"
+            for _ in range(depth):
+                source = f'{prefix}"{{{source}}}"'
+            return source
+
+        for prefix in ("f", "t"):
+            with self.subTest(prefix=prefix):
+                self._get_tokens(nested_string(149, prefix))
+                with self.assertRaisesRegex(
+                        tokenize.TokenError,
+                        "too many nested f-strings or t-strings"):
+                    self._get_tokens(nested_string(150, prefix))
+
     def test_escaped_fstring_brace_has_a_position_gap(self):
         tokens = self._get_tokens('f"a{{"', extra_tokens=True)
         self.assertEqual(