Merge pull request #25 from davidvilla/fix/mimic-generic

Support making Mimics of Generic sub-classes

Author: davidparsson

CHANGES.rst

@@ -7,6 +7,7 @@ Unreleased
 - Mock support for classmethods on instances
 - Fix namedtuple support for python 3.8 and newer
 - Fix issue with property stubbing using when() leaving stubs in setting up state
+- Allow making Mimics of Generic sub-classes
 
 20190405
 ========

doublex/doubles.py

@@ -20,6 +20,7 @@
 
 
 import inspect
+from typing import Generic
 
 import hamcrest
 
@@ -179,9 +180,10 @@ def _get_method(self, key):
         "Mimic() takes a double class as first argument (got %s instead)" & double
 
     collab_class = get_class(collab)
+    base_classes = tuple(base for base in collab_class.__bases__ if base is not Generic)
     generated_class = type(
         "Mimic_%s_for_%s" % (double.__name__, collab_class.__name__),
-        (double, collab_class) + collab_class.__bases__,
+        (double, collab_class) + base_classes,
         dict(_methods = {},
              __getattribute__ = __getattribute__hook,
              _get_method = _get_method))

doublex/test/unit_tests.py

@@ -26,6 +26,7 @@
     import thread
 except ImportError:
     import _thread as thread
+from typing import Generic, TypeVar
 
 from unittest import TestCase, skipIf
 
@@ -51,6 +52,8 @@
 from doublex.matchers import MatcherRequiredError
 from doublex.internal import InvocationContext, Method
 
+T = TypeVar('T')
+
 
 class InvocationContextTests(TestCase):
     def test_order(self):
@@ -1086,6 +1089,10 @@ class B(A):
         def method_b(self):
             return "hi"
 
+    class GenericSubclass(Generic[T]):
+        def method_c(self):
+            return "hello"
+
     def test_normal_spy_does_not_inherit_collaborator_superclasses(self):
         spy = Spy(self.B)
         assert_that(not isinstance(spy, self.B))
@@ -1135,6 +1142,13 @@ def test_mimic_mock_works(self):
 
         assert_that(mock, verify())
 
+    def test_mimic_generic_subclass_works(self):
+        stub = Mimic(Stub, self.GenericSubclass)
+        with stub:
+            stub.method_c().returns("hello")
+
+        assert_that(stub.method_c(), is_("hello"))
+
 
 class PropertyTests(TestCase):
     def test_stub_notset_property_is_None(self):