Use Microsoft.Extensions.DependencyInjection to resolve xUnit test cases.

How to use

Install the Nuget package.

Install-Package Xunit.DependencyInjection

In your testing project, add the following framework

namespace Your.Test.Project
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IDependency, DependencyClass>();
        }
    }
}

Example test class.

public interface IDependency
{
    int Value { get; }
}

internal class DependencyClass : IDependency
{
    public int Value => 1;
}

public class MyAwesomeTests
{
    private readonly IDependency _d;

    public MyAwesomeTests(IDependency d) => _d = d;

    [Fact]
    public void AssertThatWeDoStuff()
    {
        Assert.Equal(1, _d.Value);
    }
}

Integration asp.net core TestHost(3.0+)

Install-Package Microsoft.AspNetCore.TestHost

public class Startup
{
    public void ConfigureHost(IHostBuilder hostBuilder) =>
        hostBuilder.ConfigureWebHost(webHostBuilder => webHostBuilder
            .UseTestServer()
            .Configure(Configure)
            .ConfigureServices(services => services.AddRouting()));

    private void Configure(IApplicationBuilder app) =>
        app.UseRouting().UseEndpoints(endpoints => xxx);
}

V7 new features

• Don't need to add the assembly attribute TestFramework.
• Startup does not need to inherit DependencyInjectionTestFramework.
• Configure method support multiple parameters, like asp.net core Startup.

V6 to V7 break changes

-[assembly: TestFramework("Your.Test.Project.Startup", "Your.Test.Project")]

namespace Your.Test.Project
{
-   public class Startup : DependencyInjectionTestFramework
+   public class Startup
    {
-       public Startup(IMessageSink messageSink) : base(messageSink) { }

-       protected void ConfigureServices(IServiceCollection services)
+       public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IDependency, DependencyClass>();
        }

-       protected override IHostBuilder CreateHostBuilder() =>
-           base.CreateHostBuilder(assemblyName)
-               .ConfigureServices(ConfigureServices);

-       protected override void Configure(IServiceProvider provider)
+       public void Configure(IServiceProvider provider)
    }
}

Startup limitation

• CreateHostBuilder method

public class Startup
{
    public IHostBuilder CreateHostBuilder([AssemblyName assemblyName]) { }
}

• ConfigureHost method

public class Startup
{
    public void ConfigureHost(IHostBuilder hostBuilder) { }
}

• ConfigureServices method

public class Startup
{
    public void ConfigureServices(IServiceCollection services[, HostBuilderContext context]) { }
}

• Configure method Anything defined in ConfigureServices, can be specified in the Configure method signature. These services are injected if they're available.

How to find Startup?

Default is find Your.Test.Project.Startup, Your.Test.Project. If you want use a special Startup, you can defined XunitStartupAssembly and XunitStartupFullName in PropertyGroup section

<Project>
  <PropertyGroup>
    <XunitStartupAssembly>Abc</XunitStartupAssembly>
    <XunitStartupFullName>Xyz</XunitStartupFullName>
  </PropertyGroup>
</Project>

XunitStartupAssembly	XunitStartupFullName	Startup
		Your.Test.Project.Startup, Your.Test.Project
Abc		Abc.Startup, Abc
	Xyz	Xyz, Your.Test.Project
Abc	Xyz	Xyz, Abc

V5 to V6 break changes

namespace Your.Test.Project
{
    public class Startup : DependencyInjectionTestFramework
    {
        public Startup(IMessageSink messageSink) : base(messageSink) { }

-       protected override void ConfigureServices(IServiceCollection services)
+       protected void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IDependency, DependencyClass>();
        }

+       protected override IHostBuilder CreateHostBuilder(AssemblyName assemblyName) =>
+           base.CreateHostBuilder(assemblyName)
+               .ConfigureServices(ConfigureServices);
    }
}

How to inject ITestOutputHelper

internal class DependencyClass : IDependency
{
    private readonly ITestOutputHelperAccessor _testOutputHelperAccessor;

    public DependencyClass(ITestOutputHelperAccessor testOutputHelperAccessor)
    {
        _testOutputHelperAccessor = testOutputHelperAccessor;
    }
}

Write Microsoft.Extensions.Logging to ITestOutputHelper

    public class Startup
    {
        public void Configure(ILoggerFactory loggerFactory, ITestOutputHelperAccessor accessor) =>
            loggerFactory.AddProvider(new XunitTestOutputLoggerProvider(accessor));
    }

How to inject IConfiguration or IHostingEnvironment into Startup?

    public class Startup
    {
        public void ConfigureHost(IHostBuilder hostBuilder) =>
            hostBuilder
                .ConfigureServices((context, services) => { context.XXXX });
    }

or

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services, HostBuilderContext context)
        {
            context.XXXX;
        }
    }

How to configure IConfiguration?

    public class Startup
    {
        public void ConfigureHost(IHostBuilder hostBuilder) =>
            hostBuilder
                .ConfigureHostConfiguration(builder => { })
                .ConfigureAppConfiguration((context, builder) => { });
    }