Hotfix issue 153 (#161)

* add failing test

* minimal patch to fix test

bugbear.py

@@ -124,8 +124,10 @@ def _to_name_str(node):
     # "pkg.mod.error", handling any depth of attribute accesses.
     if isinstance(node, ast.Name):
         return node.id
-    assert isinstance(node, ast.Attribute)
-    return _to_name_str(node.value) + "." + node.attr
+    try:
+        return _to_name_str(node.value) + "." + node.attr
+    except AttributeError:
+        return _to_name_str(node.value)
 
 
 def _typesafe_issubclass(cls, class_or_tuple):

tests/test_bugbear.py

@@ -340,6 +340,20 @@ def test_does_not_crash_on_site_code(self):
                     if f.endswith(".py"):
                         BugBearChecker(filename=str(Path(dirname) / f))
 
+    def test_does_not_crash_on_tuple_expansion_in_except_statement(self):
+        # akin to test_does_not_crash_on_any_valid_code
+        # but targets a rare case that's not covered by hypothesmith.from_grammar
+        # see https://github.com/PyCQA/flake8-bugbear/issues/153
+        syntax_tree = ast.parse(
+            "grey_list = (ValueError,)\n"
+            "black_list = (TypeError,)\n"
+            "try:\n"
+            "    int('1e3')\n"
+            "except (*grey_list, *black_list):\n"
+            "     print('error caught')"
+        )
+        BugBearVisitor(filename="<string>", lines=[]).visit(syntax_tree)
+
 
 if __name__ == "__main__":
     unittest.main()