Simplify Your Unit Tests With Auto Mocking: Part 1 – Helper Methods
After working on the Ninject.RhinoMocks automocking container, I started using it in my current project right away and it wasn’t long before I started simplifying the usage of it with helper methods in my base test class.
From “MockingKernel.Get()” To “Get()”
I got tired of calling MockingKernel.Get
1: protected T Get<T>()
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<pre><span style="color: #606060"> 2:</span> {</pre>
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<pre><span style="color: #606060"> 3:</span> <span style="color: #0000ff">return</span> MockingKernel.Get<T>();</pre>
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<pre><span style="color: #606060"> 4:</span> }</pre>
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This is a small change, but it makes a lot of code easier to ready. Compare this:
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<pre><span style="color: #606060"> 1:</span> [Test]</pre>
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<pre><span style="color: #606060"> 2:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_that_thing()</pre>
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<pre><span style="color: #606060"> 3:</span> {</pre>
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<pre><span style="color: #606060"> 4:</span> MockingKernel.Get<IMyView>().AssertWasCalled(v => v.ThatThing());</pre>
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<pre><span style="color: #606060"> 5:</span> }</pre>
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To this:
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<pre><span style="color: #606060"> 1:</span> [Test]</pre>
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<pre><span style="color: #606060"> 2:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_that_thing()</pre>
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<pre><span style="color: #606060"> 3:</span> {</pre>
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<pre><span style="color: #606060"> 4:</span> Get<IMyView>().AssertWasCalled(v => v.ThatThing());</pre>
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<pre><span style="color: #606060"> 5:</span> }</pre>
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A small amount of code reduction and a little easier to read.
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From “Get<IMyView>().AssertWasCalled(…)” to “AssertWasCalled<IMyView>(…)”
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After adding the Get<T> code, I realized that I could simplify the assertion even further by creating a helper method that would call Get<T> for me. RhinoMocks has two methods for AssertWasCalled. The first just takes the method and sets some defaults, like only expecting 1 call. The second allows you to specify method options for more advanced needs. I created to AssertWasCalled<T> methods to mimic the RhinoMocks methods and call Get<T> for me:
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<pre><span style="color: #606060"> 1:</span> <span style="color: #0000ff">protected</span> <span style="color: #0000ff">void</span> AssertWasCalled<T>(Action<T> action)</pre>
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<pre><span style="color: #606060"> 2:</span> {</pre>
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<pre><span style="color: #606060"> 3:</span> T mock = Get<T>();</pre>
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<pre><span style="color: #606060"> 4:</span> mock.AssertWasCalled(action);</pre>
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<pre><span style="color: #606060"> 5:</span> }</pre>
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<pre><span style="color: #606060"> 6:</span> </pre>
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<pre><span style="color: #606060"> 7:</span> <span style="color: #0000ff">protected</span> <span style="color: #0000ff">void</span> AssertWasCalled<T>(Action<T> action, Action<IMethodOptions<<span style="color: #0000ff">object</span>>> methodOptions)</pre>
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<pre><span style="color: #606060"> 8:</span> {</pre>
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<pre><span style="color: #606060"> 9:</span> T mock = Get<T>();</pre>
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<pre><span style="color: #606060"> 10:</span> mock.AssertWasCalled(action, methodOptions);</pre>
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<pre><span style="color: #606060"> 11:</span> }</pre>
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This allowed me to simplify my specs down even further:
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<pre><span style="color: #606060"> 1:</span> [Test]</pre>
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<pre><span style="color: #606060"> 2:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_that_thing()</pre>
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<pre><span style="color: #606060"> 3:</span> {</pre>
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<pre><span style="color: #606060"> 4:</span> AssertWasCalled<IMyView>(v => v.ThatThing());</pre>
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<pre><span style="color: #606060"> 5:</span> }</pre>
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<pre><span style="color: #606060"> 6:</span>  </pre>
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<pre><span style="color: #606060"> 7:</span> [Test]</pre>
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<pre><span style="color: #606060"> 8:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_the_other_thing_twice()</pre>
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<pre><span style="color: #606060"> 9:</span> {</pre>
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<pre><span style="color: #606060"> 10:</span> AssertWasCalled<IMyView>(v => v.TheOtherThing(), mo => mo.Repeat.Twice());</pre>
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<pre><span style="color: #606060"> 11:</span> }</pre>
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This is less code to read and easier to understand.
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A Full Spec Example
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With these helper methods in place, a full specification is much easier to read, now:
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<pre><span style="color: #606060"> 1:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">class</span> when_doing_something_with_that_thing : ContextSpecification</pre>
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<pre><span style="color: #606060"> 2:</span> {</pre>
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<pre><span style="color: #606060"> 3:</span> <span style="color: #0000ff">protected</span> MyPresenter SUT;</pre>
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<pre><span style="color: #606060"> 4:</span> </pre>
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<pre><span style="color: #606060"> 5:</span> <span style="color: #0000ff">protected</span> <span style="color: #0000ff">override</span> <span style="color: #0000ff">void</span> EstablishContext()</pre>
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<pre><span style="color: #606060"> 7:</span> SUT = Get<MyPresenter>();</pre>
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<pre><span style="color: #606060"> 8:</span> }</pre>
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<pre><span style="color: #606060"> 9:</span> </pre>
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<pre><span style="color: #606060"> 10:</span> <span style="color: #0000ff">protected</span> <span style="color: #0000ff">override</span> <span style="color: #0000ff">void</span> When()</pre>
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<pre><span style="color: #606060"> 11:</span> {</pre>
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<pre><span style="color: #606060"> 12:</span> SUT.DoSomething();</pre>
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<pre><span style="color: #606060"> 13:</span> }</pre>
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<pre><span style="color: #606060"> 14:</span> </pre>
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<pre><span style="color: #606060"> 15:</span> [Test]</pre>
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<pre><span style="color: #606060"> 16:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_that_thing()</pre>
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<pre><span style="color: #606060"> 17:</span> {</pre>
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<pre><span style="color: #606060"> 18:</span> AssertWasCalled<IMyView>(v => v.ThatThing());</pre>
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<pre><span style="color: #606060"> 19:</span> }</pre>
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<pre><span style="color: #606060"> 20:</span>  </pre>
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<pre><span style="color: #606060"> 21:</span> [Test]</pre>
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<pre><span style="color: #606060"> 22:</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">void</span> it_should_do_the_other_thing_twice()</pre>
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<pre><span style="color: #606060"> 23:</span> {</pre>
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<pre><span style="color: #606060"> 24:</span> AssertWasCalled<IMyView>(v => v.TheOtherThing(), mo => mo.Repeat.Twice());</pre>
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<pre><span style="color: #606060"> 25:</span> }</pre>
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<pre><span style="color: #606060"> 26:</span> }</pre>
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But Wait! There’s More!
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It gets even better! In tomorrow’s blog post – part 2 of simplifying unit tests with automocking – I’ll reduce the full specification code even further by eliminating the need to declare and setup the System Under Test (SUT).
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