Crashes on empty elems (#58)

MarcoGorelli · web-flow · commit d52670a96454 · 2023-02-14T11:37:02.000-08:00
closes #57
diff --git a/autotyping/guess_type.py b/autotyping/guess_type.py
@@ -34,8 +34,8 @@ def guess_type_from_argname(name: str) -> Tuple[Optional[str], List[str]]:
     # (container)_of_<name>(s)
     # e.g. set_of_widths => Set[int]
     m = re.fullmatch(
-        rf"(?P<elems>\w*?)_?(?P<container>{containers})", name
-    ) or re.fullmatch(rf"(?P<container>{containers})_of_(?P<elems>\w*)", name)
+        rf"(?P<elems>\w+?)_?(?P<container>{containers})", name
+    ) or re.fullmatch(rf"(?P<container>{containers})_of_(?P<elems>\w+)", name)
     if m:
         # only do a simple container match
         # and don't check all of BOOL_NAMES to not trigger on stuff like "save_list"
diff --git a/tests/test_codemod.py b/tests/test_codemod.py
@@ -330,6 +330,17 @@ def __exit__(self, a, b, c, d):
         """
         self.assertCodemod(before, after, annotate_magics=True)
 
+    def test_empty_elems(self) -> None:
+        before = """
+            def foo(iterables):
+                ...
+        """
+        after = """
+            def foo(iterables) -> None:
+                ...
+        """
+        self.assertCodemod(before, after, none_return=True, guess_common_names=True)
+
     def test_annotate_imprecise_magics(self) -> None:
         before = """
             def __iter__():
