fix endless loop in redirects

tests/test_components.py

@@ -3,12 +3,32 @@ import pytest
 
 import rio
 
+
 # Sometimes components need a custom `__init__` method, and it's easy to
 # overlook mutable default values when you turn the type annotations into
 # constructor parameters. This can lead to components sharing state ACROSS
 # SESSIONS, which is REALLY REALLY bad. Make sure there are no constructors with
 # mutable default arguments.
-all_components = list(introspection.get_subclasses(rio.Component))
+def is_mutable(value: object) -> bool:
+    if value is None:
+        return False
+
+    if isinstance(value, (int, float, str, bytes)):
+        return False
+
+    if value == ():
+        return False
+
+    return True
+
+
+# We have to be careful here not to pick up any Components from test files. It
+# makes vscode extremely confused and unable to run the tests.
+all_components = [
+    obj
+    for obj in vars(rio).values()
+    if isinstance(obj, type) and issubclass(obj, rio.Component)
+]
 
 
 @pytest.mark.parametrize(
@@ -19,7 +39,7 @@ def test_constructor_has_no_mutable_defaults(cls: type):
     params_with_mutable_defaults = [
         parameter.name
         for parameter in constructor_signature.parameter_list
-        if isinstance(parameter.default, (list, dict, set))
+        if parameter.has_default and is_mutable(parameter.default)
     ]
 
     assert not params_with_mutable_defaults, (