track stubbed calls in call history

lib/spy/instance.rb

@@ -106,6 +106,7 @@ def apply(method_call)
       runner =
         if @internal[:instead]
           proc do
+            @call_history << method_call
             result = @internal[:instead].call(method_call)
           end
         else

test/instead_test.rb

@@ -70,5 +70,14 @@ def name; 'josh'; end
       o.value = 1
       assert_equal 'lauren', o.name
     end
+
+    it 'records the call in call history' do
+      o = Object.new
+      spy = Spy.on(o, :to_s).instead { 'moo' }
+
+      o.to_s
+
+      assert spy.called?
+    end
   end
 end