InlineAutoDataAttribute but for NUnit (for TestCase and TestCaseSource)

Question

To be succint:

class AutoMoqDataAttribute : AutoDataAttribute
{
    public AutoMoqDataAttribute() : base(new Fixture().Customize(new AutoMoqCustomization()))
    {
    }
}

public interface IWeapon { bool LaunchAtEarth(double probabilityOfHitting); }

public class DeathStar
{
    readonly IWeapon _weapon;

    public DeathStar(IWeapon weapon) // guard clause omitted for brevity
    {
        this._weapon = weapon;
    }

    public bool FireFromOrbit(double probabilityOfHitting)
    {
        return this._weapon.LaunchAtEarth(probabilityOfHitting);
    }
}

// Make me pass, pretty please with a cherry on the top
[Test, AutoMoqData]
[TestCase(0.1), TestCase(0.5), TestCase(1)]
public void AutoMoqData_should_fill_rest_of_arguments_that_are_not_filled_by_TestCase(
    double probabilityOfHitting,
    [Frozen] Mock<IWeapon> weapon,
    DeathStar platform)
{
    Assert.That(weapon, Is.Not.Null);
    Assert.That(platform, Is.Not.Null);
} // Ignored with error: Wrong number of parameters specified.

// Make me pass, too!
[Test, AutoMoqData]
[TestCaseSource("GetTestCases")]
public void AutoMoqData_should_fill_rest_method_arguments_that_are_not_filled_by_TestCaseSource(
    double probabilityOfHitting,
    [Frozen] Mock<IWeapon> weapon,
    DeathStar platform)
{
    Assert.That(weapon, Is.Not.Null);
    Assert.That(platform, Is.Not.Null);
} // Ignored with error: Wrong number of parameters specified.

IEnumerable<TestCaseData> GetTestCases()
{
    yield return new TestCaseData(0.1);
    yield return new TestCaseData(0.5);
    yield return new TestCaseData(1);
}

This seems to do the trick if I were using Xunit: http://nikosbaxevanis.com/blog/2011/08/25/combining-data-theories-in-autofixture-dot-xunit-extension/ I cannot find anything equivalent for NUnit.

This: http://gertjvr.wordpress.com/2013/08/29/my-first-open-source-contribution/ seems to be already working in the current version of AutoFixture.NUnit2 (the AutoData attribute), but it doesn't handle the case when I want to make it take a params object[] such that the first parameters in the test method are filled using the attribute arguments and the rest are passed through to the AutoData attribute.

Can someone guide me towards the right direction ? There seems to be something missing I cannot grasp.

Answer 1

I've got it working.

Unfortunately, due to some bad design choices in NUnit's extensibility API in 2.6 (no way to override or remove any of the built-in test case providers), I was forced to resort to some reflection to get at the internal ExtensionCollection instance in the "TestCaseProviders" class.

TL;DR: This should work in NUnit 2.6.x only. NUnit 3.0 is NOT compatible.

How to use

Just add the supplied [AutoMoqData] on a test already using the regular [TestCase] and [TestCaseSource] attributes. Test case parameters will be filled first and the rest of the test method arguments will be handled via AutoFixture. You may change the AutoMoqDataAttribute to use any different fixture customization (example: AutoRhinoMockCustomization) as you wish.

How to get it working with ReSharper's test runner

If you add this to an external assembly and reference it in your test project, NUnit won't see your add-in (because it only looks in the immediate test assembly being loaded or in DLLs in an "addins" subfolder of the currently running test runner executable.

In such case, just make an empty class in the current test project and make it inherit from AutoMoqDataAddIn. Tested using ReSharper unit test runner and it sees the test cases properly and auto-generates the test case names using only the "real" test parameters.

Show me the code!

GitHub: https://gist.github.com/rwasef1830/ab6353b43bfb6549b396