Derik Whittaker

One of the new features that is part of the next release of StructureMap 2.5 is a AutoMocking Container. 

What is an AutoMocking Container, well per Jacob over at Eleutian an AutoMocker is

AutoMockingContainer is simply a IoCContainer with a custom facility and dependency resolver that supplies a Mock (RhinoMock) for any interface that is resolved.

My definition is a little more straight forward and uses simpler word (remember I am a simpleton :))

An AutoMocking container is simply a tool that will inject mock dependencies into your object for you.

What I want to do today is show how an AutoMocking Container can reduce the amount of code/noise from your tests.   I am going to first show a tests that simply uses RhinoMocks then that same test that uses the RhinoAutoMocker

Test with only RhinoMocks

[Test]
public void NoAutoMocker()
{
	var mockProvider = MockRepository.GenerateMock<IPersistingRulesProvider>();
        var mockRepository = MockRepository.GenerateMock<ISynchronizationRepository>();
        var mockPersistanceProvider = MockRepository.GenerateMock<IPersistanceProvider>();
        var mockLogger = MockRepository.GenerateMock<ILogger>();

	// Expectations
        mockProvider.Expect(x => x.ExecuteRules(null)).IgnoreArguments().Throw(new Exception("Do not care what this is"));
        mockRepository.Expect(x => x.StartTransaction()).Repeat.Once();
        mockRepository.Expect(x => x.RollbackTransaction()).Repeat.Once();
        mockRepository.Expect( x => x.CommitTransaction() ).Repeat.Never();

	var persitingPipeline = new PersistingPipeline(mockProvider, mockPersistanceProvider, mockRepository, mockLogger);
        var result = persitingPipeline.PersistChanges(new DataSet(), 0, 0, 0);

	Assert.That( result, Is.Not.Empty );

	mockRepository.VerifyAllExpectations();
}

This code above has a bit of noise.  Because my object has a dependency on 4 other objects i need to create mocks for each of these.  This creates more work and just adds to the test noise.

Test with the RhinoAutoMocker

[Test]
public void WithAutoMocker()
{
	var mockPipeline = new RhinoAutoMocker<PersistingPipeline>();

	mockPipeline.Get<IPersistingRulesProvider>().Expect( x => x.ExecuteRules( null ) ).IgnoreArguments().Throw( new Exception( "Do not care what this is" ) );
	mockPipeline.Get<ISynchronizationRepository>().Expect(x => x.StartTransaction()).Repeat.Once();
        mockPipeline.Get<ISynchronizationRepository>().Expect(x => x.RollbackTransaction()).Repeat.Once();
        mockPipeline.Get<ISynchronizationRepository>().Expect(x => x.CommitTransaction()).Repeat.Never();

	var result = mockPipeline.ClassUnderTest.PersistChanges( new DataSet(), 0, 0, 0 );

	Assert.That( result, Is.Not.Empty );

}

The code above does not require me to create mocks for each of my dependencies, the AutoMocker will do that for me.

Also notice that when I need to set an expectation for a dependencies I can access it via the .Get<>() method. 

Till next time,

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