.net - 我应该如何模拟这个简单的服务层方法？

Question

我的服务层中有以下简单方法。我不确定应该如何模拟不同的链接部分，从存储库开始？

public ICollection<GameFile> FindAllActiveGamesFiles()
{
    return _gameFileRepository // <- this is an IRepository<GameFile>
        .Find() // <-- returns an IQueryable<T> .. in this case, an IQueryable<GameFile>
        .WhereIsActive() // <-- a simple Pipe/Filter; 'where x.IsActive'
        .ToList();
}

我更喜欢使用最小起订量，但我很高兴看到其他暗示.. 主要是因为我不是在寻找确切的语法答案，而是在寻找理论答案。 IE。你需要模拟 IRepository<GameFile>并设置 ToList()只有方法..等等等等......

这就是我不明白我应该 mock 的东西。

干杯:)

---更新:澄清我的问题

我要测试的是“FindAllActiveGamesFiles()”方法是否有效。因此，我相信我需要模拟 gameFileRepository(这是一个接口(interface))。我不确定这是否是我应该在此示例中模拟的唯一内容。

例如。

[TestMethod]
public void MyTest()
{
    // Arrange.
    Mock<IRepository<GameFile>> mockRepository = new Mock<IRepository<GameFile>>();
    mockRepository.Setup(....).MoreStuffToDo(...); // <-- that's what i'm unsure about.
    IGameFileService = new GameFileService(mockRepository, fakeLoggingService);

    // Act.
    var gameFiles = gameFileService.FindAllActiveGamesFiles();

    // Asserts.
    Assert.IsNotNull(gameFiles);
    CollectionAssert.AllItemsAreNotNull(gameFiles.ToArray());
    // .. and more asserts ///
    // What about expectations? eg. that ToList() was entered/called?
}

Answer 1

听起来您想编写一个测试来演示您的 Linq 语句的覆盖率。您已经指出您的存储库是一个接口(interface) (IRepository ) 并且应该被模拟。您只需要一些示例来说明您的服务层如何正确过滤存储库的内容。

这是我理解的 ServiceLayer。

public class ServiceLayer
{
     private readonly IRepository<GameFile> _gameRepository;

     public SerivceLayer(IRepository<GameFile> repository)
     {
         _gameRepository = repository;
     }

     public IEnumerable<GameFile> FindAllActiveGamesFiles()
     {
         return _gameRepository
                    .Find()  // method we need to mock
                    .Where( gameFile => gameFile.IsActive)
                    .ToList();
     }
}

让我们写一些测试....(NUnit 和 Moq)

[TestFixture]
public class ServiceLayerFixture
{
      protected IRepository<GameFile> Repository;
      protected ServiceLayer Subject;
      protected ICollection<GameFile> Results;

      [Setup]
      public void Setup()
      {
          // create our mock
          Repository = new Mock<IRepository<GameFile>>().Object;

          // initialize our test subject
          Subject = new ServiceLayer(Repository);
      }

      [Test]
      public void WhenRepositoryDoesNotContainItems_ServiceLayer_ReturnsAnEmptyCollection()
      {
         Mock.Get(Repository)
             .Setup( r => r.Find())
             .Returns( new List<GameFile>().AsQueryable() );

         Results = Subject.FindAllActiveGameFiles();

         Assert.AreEqual(0, Results.Count);
      }

      [Test]
      public void WhenRepositoryDoesNotContainActiveItems_ServiceLayer_ReturnsAnEmptyCollection()
      {
         Mock.Get(Repository)
             .Setup( r => r.Find())
             .Returns( 
                 new List<GameFile>()
                     {
                        new GameFile { IsActive = false },
                        new GameFile { IsActive = false }
                     }.AsQueryable() );

         Results = Subject.FindAllActiveGameFiles();

         Assert.AreEqual(0, Results.Count);            
      }

      [Test]
      public void WhenRepositoryContainActiveItems_ServiceLayer_FiltersItemsAppropriately()
      {
         Mock.Get(Repository)
             .Setup( r => r.Find())
             .Returns( 
                 new List<GameFile>()
                     {
                        new GameFile { IsActive = true },
                        new GameFile { IsActive = false }
                     }.AsQueryable() );

         Results = Subject.FindAllActiveGameFiles();

         Assert.AreEqual(1, Results.Count);            
      }
}

您的代码停止的地方在于您可以更优雅地处理来自 IRepository 的异常。

所以考虑:

[Test]
public void WhenTheRepositoryFails_ServiceLayer_ShouldHandleExceptionsGracefully()
{
    Mock.Get(Repository)
        .Setup( r => r.Find())
        .Throws( new InvalidOperationException() );

    Results = Subject.FindAllActiveGameFiles();

    Assert.AreEqual(0, Results.Count);          
}

或者，也许您想包装异常？

[Test]
[ExpectedException(typeof(GameFileNotFoundException))]
public void WhenTheRepositoryFails_ServiceLayer_ShouldReportCustomError()
{
    Mock.Get(Repository)
        .Setup( r => r.Find())
        .Throws( new InvalidOperationException() );

    Subject.FindAllActiveGameFiles();
}