bpo-40864: Fetch instance variables for spec

Lib/unittest/mock.py

@@ -487,8 +487,13 @@ class NonCallableMock(Base):
         _spec_class = None
         _spec_signature = None
         _spec_asyncs = []
+        try:
+            _members = inspect.getmembers(spec)
+        except Exception:
+            # Fallback to dir if for some reason we cannot inspect members
+            _members = [(elem, None) for elem in dir(spec)]
 
-        for attr in dir(spec):
+        for attr, _ in _members:
             if iscoroutinefunction(getattr(spec, attr, None)):
                 _spec_asyncs.append(attr)
 
@@ -501,7 +506,11 @@ class NonCallableMock(Base):
                                         _spec_as_instance, _eat_self)
             _spec_signature = res and res[1]
 
-            spec = dir(spec)
+            spec = []
+            for member_k, member_v in _members:
+                spec.append(member_k)
+                if member_k == '__init__' and hasattr(member_v, '__code__'):
+                    spec.extend(member_v.__code__.co_names)
 
         __dict__ = self.__dict__
         __dict__['_spec_class'] = _spec_class

Lib/unittest/test/testmock/testmock.py

@@ -1,4 +1,5 @@
 import copy
+import inspect
 import re
 import sys
 import tempfile
@@ -868,6 +869,20 @@ class MockTest(unittest.TestCase):
         self.assertRaises(AttributeError, set_attr)
 
 
+    def test_finds_attrs_set_in__init__(self):
+        class X(object):
+            y = 3
+
+            def __init__(self, z):
+                self.z = self.__get_z()
+
+            def __get_z(self): return 'Z'
+
+        mock = Mock(spec=X)
+        self.assertTrue(hasattr(mock, 'y'))
+        self.assertTrue(hasattr(mock, 'z'))
+
+
     def test_copy(self):
         current = sys.getrecursionlimit()
         self.addCleanup(sys.setrecursionlimit, current)