when mock_model receives destroy, set its id to nil

lib/rspec/rails/mocks.rb

@@ -22,6 +22,10 @@ def new_record?
         def persisted?
           !!id
         end
+
+        def destroy
+          self.stub(:id) { nil }
+        end
       end
 
       # Creates a mock object instance for a +model_class+ with common

spec/rspec/rails/mocks/mock_model_spec.rb

@@ -14,6 +14,14 @@
     end
   end
 
+  describe "destroy" do
+    it "sets id to nil" do
+      model = mock_model(MockableModel)
+      model.destroy
+      model.id.should be_nil
+    end
+  end
+
   describe "with params" do
     it "does not mutate its parameters" do
       params = {:a => 'b'}