Fix bug where methods on subclasses failed when using Replace.on_class

testfixtures/replace.py

@@ -148,7 +148,7 @@ def _find_container(self, attribute, name: str, break_on_static: bool):
         for referrer in get_referrers(attribute):
             if break_on_static and isinstance(referrer, staticmethod):
                 return None, referrer
-            elif isinstance(referrer, dict) and '__dict__' in referrer:
+            elif isinstance(referrer, dict):
                 if referrer.get(name) is attribute:
                     for container in get_referrers(referrer):
                         if isinstance(container, type):

testfixtures/tests/test_replace.py

@@ -764,6 +764,36 @@ def method(self, x):
         compare(sample.method(1), expected=2)
         assert SampleClass.__dict__['method'] is original
 
+    def test_method_on_subclass(self):
+
+        class SampleClass:
+
+            def method_a(self, x):
+                return x*2
+
+        class SampleSubClass(SampleClass):
+            """
+            Some doc!
+            """
+
+            def method_b(self, x):
+                return x*3
+
+        original_a = SampleClass.__dict__['method_a']
+        original_b = SampleSubClass.__dict__['method_b']
+        sample = SampleSubClass()
+
+        with Replacer() as replace:
+            replace.on_class(SampleSubClass.method_a, lambda self, x: x*4)
+            replace.on_class(SampleSubClass.method_b, lambda self, x: x*5)
+            compare(sample.method_a(1), expected=4)
+            compare(sample.method_b(1), expected=5)
+
+        compare(sample.method_a(1), expected=2)
+        compare(sample.method_b(1), expected=3)
+        assert SampleClass.__dict__['method_a'] is original_a
+        assert SampleSubClass.__dict__['method_b'] is original_b
+
     def test_attributes_on_class(self):
 
         class SampleClass: