NUnit test fixture hierarchies

Question

I'm trying to create some kind of implementation-agnostic fixture. Say I have the following interface. ``` public interface ISearchAlgorithm { // methods } ``` And I know exactly how it should behave, so I want to run the same set of tests for every derived class: ``` public class RootSearchAlgorithmsTests { private readonly ISearchAlgorithm _searchAlgorithm; public RootSearchAlgorithmsTests(ISearchAlgorithm algorithm) { _searchAlgorithm = algorithm; } [Test] public void TestCosFound() { // arrange // act with _searchAlgorithm // assert } [Test] public void TestCosNotFound() { // arrange // act with _searchAlgorithm // assert } // etc ``` Then I create the following fixtures for each derived class: ``` [TestFixture] public class BinarySearchTests : RootSearchAlgorithmsTests { public BinarySearchTests(): base(new BinarySearchAlgorithm()) {} } [TestFixture] public class NewtonSearchTests : RootSearchAlgorithmsTests { public NewtonSearchTests(): base(new NewtonSearchAlgorithm()) {} } ```…

Accepted Answer

You can use Generic Test Fixtures in NUnit to achive what you want.

```
[TestFixture(typeof(Implementation1))]
[TestFixture(typeof(Implementation2))]
public class RootSearchAlgorithmsTests<T> where T : ISearchAlgorithm, new()
{
    private readonly ISearchAlgorithm _searchAlgorithm;

[SetUp]
    public void SetUp()
    {
        _searchAlgorithm = new T();
    }

[Test]
    public void TestCosFound()
    {
        // arrange
        // act with _searchAlgorithm
        // assert
    }

[Test]
    public void TestCosNotFound()
    {
        // arrange
        // act with _searchAlgorithm
        // assert
    } 
    // etc
}
```

NUnit test fixture hierarchies

Solution

Problem