There are certainly cases when developers want to run integration tests against their code wired up heavily by dependency injection. xUnit is a mature, loved-by-developers, and robust test framework for testing .net code. A slight downside of xUnit is that it lacks an out-of-the-box solution to inject dependencies. Fortunately, xUnit has been equipped with the “Fixture” feature, which is meant to share contexts among test classes or tests within the same test class. This feature can be leveraged to retain dependency injection containers among test classes in an xUnit-powered test project.
Several key steps are involved in utilizing dependency injection in an xUnit test project covered below.
Defining a class to retain dependency injection provider’s instance
We need to define a class to instantiate Microsoft’s dependency injection service provider to add services and configurations. We’d call this class TestBedFixture and have it implement IDisposable and optionally IAsyncDisposable interface(s). We require to add two key methods to this class to facilitate accessing the wired up services’ instances. They are per the following code snippets:
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public T GetScopedService<T>(ITestOutputHelper testOutputHelper)
{
var serviceProvider = GetServiceProvider(testOutputHelper);
using var scope = serviceProvider.CreateScope();
return scope.ServiceProvider.GetService<T>();
}
public T GetService<T>(ITestOutputHelper testOutputHelper)
=> GetServiceProvider(testOutputHelper).GetService<T>();
This source code illustrates a full-fledge implementation of a functional fixture class whose instance can be used by other test classes.
Defining a fixture class
The next step is to decorate the test class with IClassFixture interface to leverage the dependency injection’s container to acquire services’ instances by invoking GetService or GetScopedService methods. This code snippet illustrates this approach.
This open-source C# project facilitates using Microsoft dependency injection in xUnit test projects.
To use this project in actual test projects, install the NuGet package of Xunit.Microsoft.DependencyInjection from https://NuGet.org.
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Install-Package Xunit.Microsoft.DependencyInjection