[strict_mock] Add support mocking other mocks

Fixes facebook#130

testslide/strict_mock.py

@@ -8,17 +8,41 @@
 import functools
 import inspect
 import os.path
+from unittest.mock import Mock, PropertyMock, AsyncMock, MagicMock, NonCallableMagicMock, _must_skip
 
-from unittest.mock import _must_skip
 from .lib import _validate_function_signature
 
 
+def _get_spec_from_strict_mock(mock_obj: StrictMock) -> Optional[Type]:
+    if "__template" in mock_obj.__dict__:
+        return mock_obj.__template
+
+    return None
+
+
+def _get_spec_from_mock(mock_obj: Mock) -> Optional[Type]:
+    if "_spec_class" in mock_obj.__dict__:
+        return mock_obj._spec_class
+
+    return None
+
+
+MOCK_TO_TEMPLATE_EXTRACTORS = {
+    StrictMock: _get_spec_from_strict_mock,
+    Mock: _get_spec_from_mock,
+    PropertyMock: _get_spec_from_mock,
+    AsyncMock: _get_spec_from_mock,
+    MagicMock: _get_spec_from_mock,
+    NonCallableMagicMock: _get_spec_from_mock,
+}
+
+
 def _wrap_signature_and_type_validation(value, template, attr_name):
-    if isinstance(template, StrictMock):
-        if "_template" in template.__dict__:
-            template = template._template
-        else:
-            return value
+    template = MOCK_TO_TEMPLATE_EXTRACTORS.get(
+        type(self.__template), lambda x: None
+    )()
+    if not template
+        return value
 
     # This covers runtime attributes
     if not hasattr(template, attr_name):