Moq IServiceProvider/IServiceScope

Question

我正在尝试创建一个模拟(使用Moq),IServiceProvider以便我可以测试我的存储库类:

public class ApiResourceRepository : IApiResourceRepository
{
    private readonly IServiceProvider _serviceProvider;

    public ApiResourceRepository(IServiceProvider serviceProvider)
    {
        _serviceProvider = serviceProvider;
        _dbSettings = dbSettings;
    }

    public async Task<ApiResource> Get(int id)
    {
        ApiResource result;

        using (var serviceScope = _serviceProvider.
            GetRequiredService<IServiceScopeFactory>().CreateScope())
        {
            var context = serviceScope.ServiceProvider.GetRequiredService<ConfigurationDbContext>();
            result = await
                context.ApiResources
                .Include(x => x.Scopes)
                .Include(x => x.UserClaims)
                .FirstOrDefaultAsync(x => x.Id == id);
        }

        return result;
    }
}

我创建Mock对象的尝试如下:

Mock<IServiceProvider> serviceProvider = new Mock<IServiceProvider>();

serviceProvider.Setup(x => x.GetRequiredService<ConfigurationDbContext>())
    .Returns(new ConfigurationDbContext(Options, StoreOptions));

Mock<IServiceScope> serviceScope = new Mock<IServiceScope>();

serviceScope.Setup(x => x.ServiceProvider).Returns(serviceProvider.Object);

serviceProvider.Setup(x => x.CreateScope()).Returns(serviceScope.Object);

我收到以下错误:

System.NotSupportedException:Expression引用不属于模拟对象的方法:x => x.GetRequiredService()

Answer 1

如前所述,Moq不允许设置扩展方法.

然而,在这种情况下,所述扩展方法的源代码在Github上可用

ServiceProviderServiceExtensions.

解决这类问题的常用方法是找出扩展方法的作用,并通过它的执行安全地模拟路径.

所有这些中的基本类型是IServiceProvider它的object Getservice(Type type)方法.此方法是解析服务类型时最终调用的方法.而且我们只处理抽象(接口),这使得使用moq变得更加容易.

//Arrange
var serviceProvider = new Mock<IServiceProvider>();
serviceProvider
    .Setup(x => x.GetService(typeof(ConfigurationDbContext)))
    .Returns(new ConfigurationDbContext(Options, StoreOptions));

var serviceScope = new Mock<IServiceScope>();
serviceScope.Setup(x => x.ServiceProvider).Returns(serviceProvider.Object);

var serviceScopeFactory = new Mock<IServiceScopeFactory>();
serviceScopeFactory
    .Setup(x => x.CreateScope())
    .Returns(serviceScope.Object);

serviceProvider
    .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
    .Returns(serviceScopeFactory.Object);

var sut = new ApiResourceRepository(serviceProvider.Object);

//Act
var actual = sut.Get(myIntValue);

//Asssert
//...

查看上面的代码,您将看到该安排如何满足扩展方法的预期行为,并通过扩展(无双关语)测试方法.

Answer 2

以防万一它对某人有用，这里有一个示例，说明我如何按照此处的建议为我的单元测试创​​建自己的 ServiceProvider 。我还添加了 ServiceScope 和 ServiceScopeFactory 模拟来提供所有服务。

这是我的单元测试中的代码：

var serviceCollection = new ServiceCollection();

// Add any DI stuff here:
serviceCollection.AddSingleton<ILogger>(loggerMock.Object);

// Create the ServiceProvider
var serviceProvider = serviceCollection.BuildServiceProvider();

// serviceScopeMock will contain my ServiceProvider
var serviceScopeMock = new Mock<IServiceScope>();
serviceScopeMock.SetupGet<IServiceProvider>(s => s.ServiceProvider)
    .Returns(serviceProvider);

// serviceScopeFactoryMock will contain my serviceScopeMock
var serviceScopeFactoryMock = new Mock<IServiceScopeFactory>();
serviceScopeFactoryMock.Setup(s => s.CreateScope())
    .Returns(serviceScopeMock.Object);
    

然后我可以将 serviceScopeFactoryMock 传递给 sut 构造函数。

这是正在测试的代码：

using (var scope = _serviceScopeFactory.CreateScope())
{
    var logger = scope.ServiceProvider.GetRequiredService<ILogger>();
    ...
}

Answer 3

一般规则是您不要模拟您不拥有的类型。除非您需要验证对服务提供者的调用，否则只需在您的测试中IServiceProvider从 a构建ServiceCollection。

Answer 4

我想说的是，当您需要添加那么多仪式只是为了模拟一个简单的方法时，那么您的代码可能不太可测试。因此，另一种选择是将服务定位器隐藏在更加测试和模拟友好的界面后面（在我看来也是一个更好的界面）：

public interface IServiceLocator : IDisposable
{
    T Get<T>();
}

public class ScopedServiceLocator : IServiceLocator
{
    private readonly IServiceScopeFactory _factory;
    private IServiceScope _scope;

    public ScopedServiceLocator(IServiceScopeFactory factory)
    {
        _factory = factory;
    }

    public T Get<T>()
    {
        if (_scope == null)
            _scope = _factory.CreateScope();

        return _scope.ServiceProvider.GetService<T>();
    }


    public void Dispose()
    {
        _scope?.Dispose();
        _scope = null;
    }
}

我只GetService<T>在这里实现了该方法，但您可以轻松添加/删除，以便定位器更好地满足您的需求。以及如何使用它的示例；

public class ALongRunningTask : IRunForALongTime
{
    private readonly IServiceLocator _serviceLocator;

    public ALongRunningTask(IServiceLocator serviceLocator)
    {
        _serviceLocator = serviceLocator;
    }

    public void Run()
    {
        using (_serviceLocator)
        {
            var repository = _serviceLocator.Get<IRepository>();
        }
    }
}

Answer 5

这是我在范围服务提供商内部进行模拟的片段。对于测试 IHostedService 等很有用：

Mock<IServiceProvider> CreateScopedServicesProvider(params (Type @interface, Object service)[] services)
{
    var scopedServiceProvider = new Mock<IServiceProvider>();

    foreach (var (@interfcae, service) in services)
    {
        scopedServiceProvider
            .Setup(s => s.GetService(@interfcae))
            .Returns(service);
    }

    var scope = new Mock<IServiceScope>();
    scope
        .SetupGet(s => s.ServiceProvider)
        .Returns(scopedServiceProvider.Object);

    var serviceScopeFactory = new Mock<IServiceScopeFactory>();
    serviceScopeFactory
        .Setup(x => x.CreateScope())
        .Returns(scope.Object);

    var serviceProvider = new Mock<IServiceProvider>();
    serviceProvider
        .Setup(s => s.GetService(typeof(IServiceScopeFactory)))
        .Returns(serviceScopeFactory.Object);

    return serviceProvider;
}

用法：

var service = new Mock<IMyService>();
var serviceProvider = CreateScopedServicesProvider((typeof(IMyService), scopedService.Object));
var sut = new ServiceThatUsesScopes(serviceProvider.Object)