Added new test and changes to imr.py to address the issue

bowler/imr.py

@@ -25,6 +25,28 @@
     Node,
 )
 
+def add_argument(node, arg_name, default_value=None, after=None):
+    if node.type == TOKEN.FUNC_DEF:
+        func_args = node.children[2]
+        func_args.append_child(Node(TOKEN.ARGUMENT, arg_name))
+
+        if default_value is not None:
+            func_args.append_child(Node(TOKEN.EQUALS, "="))
+            func_args.append_child(Node(TOKEN.NUMBER, default_value))
+
+        if after is not None:
+            # Find the position after which to add the argument
+            for i, child in enumerate(func_args.children):
+                if child.value == after:
+                    pos = i + 1
+                    break
+            else:
+                pos = len(func_args.children)
+
+            func_args.insert_child(pos, Node(TOKEN.ARGUMENT, arg_name))
+
+    return node
+
 log = logging.getLogger(__name__)
 
 
@@ -47,7 +69,7 @@ def build(cls, leaf: Leaf, is_def: bool, **kwargs: Any) -> "FunctionArgument":
 
             elif leaf.type == SYMBOL.tname:
                 kwargs["name"] = leaf.children[0].value
-                kwargs["annotation"] = leaf.children[-1].value
+                kwargs["annotation"] = leaf.children[-1]
 
             elif leaf.type == TOKEN.EQUAL:
                 pass

bowler/tests/query.py

@@ -343,3 +343,19 @@ def add_bad_modifier(q):
             self.assertIn(
                 "Only the last fixer/callback may return", error.call_args[0][0]
             )
+
+    def test_function_with_type_hinting(self):
+        def f(x: 'List[str]'):
+            pass
+
+        def query_func(x):
+            return Query(x).select_function(f).add_argument("y", "5", True, "x")
+
+        self.run_bowler_modifiers(
+            [
+                ("def f(x: List[str]): pass", "def f(x: List[str], y): pass"),
+                ("def g(x: List[str]): pass", "def g(x: List[str]): pass"),
+                ("f(['test'])", "f(['test'], 5)"),
+            ],
+            query_func=query_func,
+        )