如何在ASP.NET Core MVC中对RazorViewEngineOptions进行单元测试？

Question

在从ConfigureServices调用的扩展方法中，我将EmbeddedFileProvider的实例添加到RazorViewEngineOptions。我想测试它是否已添加，但我找不到如何获取RazorViewEngineOptions实例。

这在运行应用程序时有效：

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc()
                  .SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
    services.AddMyServices(Configuration);
}

public static IServiceCollection AddMyServices(this IServiceCollection services, IConfiguration configuration)
{
    services.Configure<RazorViewEngineOptions>(options => 
    {
        options.FileProviders.Add(new EmbeddedFileProvider(typeof(MyClass).Assembly, "My.Namespace"));
    });

    return services;
}

但我该如何测试呢？在这里投掷NullReferenceException：

[Fact]
public void MyTest()
{
    var services = new ServiceCollection();
    var serviceProvider = services.BuildServiceProvider();

    MyServicesBuilder.AddMyServices(services, new Mock<IConfiguration>().Object);
    var razorOptions = serviceProvider.GetService<IOptions<RazorViewEngineOptions>>();

    Assert.Equal(1, razorOptions.Value.FileProviders.Where(x => x.GetType() == typeof(EmbeddedFileProvider)).Count());
}

我试过添加services.AddMvc()或services.AddSingleton<RazorViewEngineOptions>()。

我也尝试过调用services.GetRequiredService<RazorViewEngineOptions>()，但这会引发System.InvalidOperationException : No service for type 'Microsoft.Extensions.Options.IOptions'1[Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions

我也试过要求RazorViewEngineOptions而不是IOptions<RazorViewEngineOptions>。

Answer 1

在提供者已经构建之后添加到服务集合中的任何内容都不会被提供者知道。

添加了服务集合所需的所有内容，然后构建提供程序以执行断言

例如

[Fact]
public void MyTest() {
    //Arrange
    var services = new ServiceCollection();
    services.AddOptions();

    IConfiguration config = new ConfigurationBuilder()
        // Call additional providers here as needed.
        //...
        .Build();

    //Act
    MyServicesBuilder.AddMyServices(services, config);
    //OR
    //services.AddMyServices(config);

    //Assert
    var serviceProvider = services.BuildServiceProvider();
    var razorOptions = serviceProvider.GetService<IOptions<RazorViewEngineOptions>>();

    Assert.NotNull(razorOptions);
    Assert.Equal(1, razorOptions.Value.FileProviders.Where(x => x.GetType() == typeof(EmbeddedFileProvider)).Count());
}