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

How to use

Install the Nuget package.

dotnet add 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+)

dotnet add package Microsoft.AspNetCore.TestHost

public class Startup
{
    public void ConfigureHost(IHostBuilder hostBuilder) =>
        hostBuilder.ConfigureWebHost[Defaults](webHostBuilder => webHostBuilder
            .UseTestServer().UseStartup<AspNetCoreStartup>());
}

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?

1. Specific startup

Declare [Startup] on test class

2. Nest startup

public class TestClass1
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services) { }
    }

3. Closest startup

If the class type full name is "A.B.C.TestClass", find Startup in the following order:

1. A.B.C.Startup
2. A.B.Startup
3. A.Startup
4. Startup

4. Global 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>

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) => { });
}

[MemberData] how to inject?

Use [MethodData]

Integrate opentelemetry

TracerProviderBuilder builder;

builder.AddSource("Xunit.DependencyInjection");