Replace ast.Str usages with ast.Constant for compatibility with Python 3.14

tests/test_asttokens.py

@@ -125,7 +125,7 @@ def test_unicode_offsets(self):
 
     # Verify that ast parser produces offsets as we expect. This is just to inform the
     # implementation.
-    string_node = next(n for n in ast.walk(root) if isinstance(n, ast.Str))
+    string_node = next(n for n in ast.walk(root) if isinstance(n, ast.Constant))
     self.assertEqual(string_node.lineno, 1)
     self.assertEqual(string_node.col_offset, 4)
 

tests/test_tokenless.py

@@ -47,7 +47,7 @@ def is_fstring_format_spec(node):
       and len(node.values) == 1
       and (
           (
-              isinstance(node.values[0], ast.Str)
+              isinstance(node.values[0], ast.Constant)
               and node.values[0].value in ['.2f']
           ) or (
               isinstance(node.values[0], ast.FormattedValue)
@@ -97,7 +97,7 @@ def check_node(self, atok, node):
       atok_text = atok.get_text(node, padded=padded)
       if ast_text:
         if sys.version_info < (3, 12) and (
-          ast_text.startswith("f") and isinstance(node, (ast.Str, ast.FormattedValue))
+          ast_text.startswith("f") and isinstance(node, (ast.Constant, ast.FormattedValue))
           or is_fstring_format_spec(node)
           or (not fstring_positions_work() and is_fstring_internal_node(node))
         ):

tests/test_util.py

@@ -98,7 +98,7 @@ def test_replace(self):
     source = "foo(bar(1 + 2), 'hello' + ', ' + 'world')"
     atok = asttokens.ASTTokens(source, parse=True)
     names = [n for n in asttokens.util.walk(atok.tree) if isinstance(n, ast.Name)]
-    strings = [n for n in asttokens.util.walk(atok.tree) if isinstance(n, ast.Str)]
+    strings = [n for n in asttokens.util.walk(atok.tree) if isinstance(n, ast.Constant) and isinstance(n.value, str)]
     repl1 = [atok.get_text_range(n) + ('TEST',) for n in names]
     repl2 = [atok.get_text_range(n) + ('val',) for n in strings]
     self.assertEqual(asttokens.util.replace(source, repl1 + repl2),