1. Introduction
XUnit provides two ways of sharing data between tests – ICollectionFixture and IClassFixture. The first one allows you to shared context across collections and the second one across test classes. I’ve already had a couple of cases in which these fixtures were not enough. Basically, I wanted to share data between all tests in given assembly – without worrying in which test class or test collection given test is. In these circumstances, I’ve usually used some kind of old fashioned singleton or custom TestFrameworkExecutor. I’ve never liked those solutions, fortunately recently I’ve come across a nice little library – xunit.assemblyfixture.
2. Usage
Xunit.assemblyfixture allows you to share data between tests in given assembly via IAssemblyFixture
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public class TestFixture : IDisposable { public static int InitializationCounter { get; private set; } public TestFixture() { InitializationCounter++; } public void Dispose() { // free resources if necessary } } |
And then create test classes which implement IAssemblyFixture
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public class TestBase : IAssemblyFixture<TestFixture> { protected readonly ITestOutputHelper TestOutputHelper; protected readonly TestFixture Fixture; protected TestBase(ITestOutputHelper testOutputHelper, TestFixture fixture) { this.TestOutputHelper = testOutputHelper; this.Fixture = fixture; } protected void DisplayInitializationCount() { TestOutputHelper.WriteLine($"Initialization count: {TestFixture.InitializationCounter}"); } } |
Xunit.assemblyfixture fixture will ensure that given test class is shared via all the tests and is initialized only once.
If you want to share multiple classes across the assembly, you can, of course, use IAssemblyFixture multiple times.
3. Visual Studio 2017 – XUnit beta tests runners
As for now VS 2017 RC requires beta runners of XUnit in order to run our unit tests. xunit.assemblyfixture seems not to cooperate with them smoothly. However, there is a simple workaround to fix that. All we have to do is to add the following attribute to our test project
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[assembly: TestFramework("Xunit.TestFramework", "xunit.assemblyfixture")] |
And from now on, XUnit correctly can inject assembly fixtures into our test classes
Source code for this post can be found here