Refactor:extract stubbee_with_method to lower diff

... between
test_should_allow_stubbing_existing_*_any_instance_{,super}class_method

test/acceptance/stubbing_non_existent_any_instance_method_test.rb

@@ -33,7 +33,7 @@ def teardown
   end
 
   def test_should_allow_stubbing_existing_public_any_instance_method
-    assert_allows_stubbing_existing_any_instance_method(class_with_method(:public))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:public))
   end
 
   def test_should_allow_stubbing_method_to_which_any_instance_responds
@@ -66,11 +66,11 @@ def respond_to?(method, _include_private = false)
   end
 
   def test_should_allow_stubbing_existing_protected_any_instance_method
-    assert_allows_stubbing_existing_any_instance_method(class_with_method(:protected))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:protected))
   end
 
   def test_should_allow_stubbing_existing_private_any_instance_method
-    assert_allows_stubbing_existing_any_instance_method(class_with_method(:private))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:private))
   end
 
   def assert_allows_stubbing_existing_any_instance_method(klass)
@@ -88,6 +88,10 @@ def existing_method; end
     klass.send(visibility, :existing_method)
     klass
   end
+
+  def stubbee_with_method(visibility)
+    class_with_method(visibility)
+  end
 end
 
 class AllowStubbingExistingAnyInstanceSuperclassMethodTest < Mocha::TestCase
@@ -102,15 +106,15 @@ def teardown
   end
 
   def test_should_allow_stubbing_existing_public_any_instance_superclass_method
-    assert_allows_stubbing_existing_any_instance_method(Class.new(class_with_method(:public)))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:public))
   end
 
   def test_should_allow_stubbing_existing_protected_any_instance_superclass_method
-    assert_allows_stubbing_existing_any_instance_method(Class.new(class_with_method(:protected)))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:protected))
   end
 
   def test_should_allow_stubbing_existing_private_any_instance_superclass_method
-    assert_allows_stubbing_existing_any_instance_method(Class.new(class_with_method(:private)))
+    assert_allows_stubbing_existing_any_instance_method(stubbee_with_method(:private))
   end
 
   def assert_allows_stubbing_existing_any_instance_method(klass)
@@ -128,4 +132,8 @@ def existing_method; end
     klass.send(visibility, :existing_method)
     klass
   end
+
+  def stubbee_with_method(visibility)
+    Class.new(class_with_method(visibility))
+  end
 end