将模拟方法的结果返回到另一个模拟方法

Question

我有一个类，它有以下实现：

public sealed class HotelRepository : IHotelRepository
{
    private readonly string _dataSource;

    public HotelRepository(string dataSource) => _dataSource = dataSource;

    /// <inheritdoc />
    public async Task<IEnumerable<Hotel>> GetAllAsync() =>
        await Task.Run(() => JObject.Parse(File.ReadAllText(_dataSource))["hotels"].ToList().Select(x => x.ToObject<Hotel>()));

    /// <inheritdoc />
    public async Task<IEnumerable<Hotel>> GetListByMatchAsync(string name) =>
        await GetAllAsync().ContinueWith(x => x.Result.Where(y => y.Name.Contains(name, StringComparison.CurrentCultureIgnoreCase)));
}

如您所见，GetListByMatchAsync方法调用GetAllAsync，然后在返回结果之前执行一些逻辑。

当我试图模拟这个存储库进行单元测试时，我很难从GetListByMatchAsync中获得结果，因为它总是作为空引用异常而失败。

以下是单元测试：

[TestCase("Test", "X")]
[TestCase("Hotel", "X")]
[TestCase("Name", "X")]
public async Task GetListByMatchAsync_GetHotelListByMatchingNameAsync_ReturnsFiveMatchingHotels(string name, string nonMatch)
{

    _hotelRepositoryMock = new Mock<IHotelRepository>();
    _hotelRepository = _hotelRepositoryMock.Object;

    // Set up sample data.
    var data = new List<Hotel>
    {
        new Hotel{Id = 1, Name = $"{name}", Description = "Description2", Location = "Location2", Rating = Rating.Two},
        new Hotel{Id = 2, Name = $"{name.ToUpper()}", Description = "Description1", Location = "Location1", Rating = Rating.Five},
        new Hotel{Id = 3, Name = $"{name.ToLower()}", Description = "Description2", Location = "Location2", Rating = Rating.Three},
        new Hotel{Id = 4, Name = $"{name} {nonMatch}", Description = "Description2", Location = "Location2", Rating = Rating.One},
        new Hotel{Id = 5, Name = nonMatch, Description = "Description2", Location = "Location2", Rating = Rating.One},
    };

    // Set up mock methods and ensure these method returns any sample data.
    _hotelRepositoryMock.Setup(x => x.GetListByMatchAsync(It.IsAny<string>()));
    _hotelRepositoryMock.Setup(x => x.GetAllAsync()).ReturnsAsync(data);


    var result = await _hotelRepository.GetListByMatchAsync(name);

    // Cast to list to make assertions.
    var hotels = result.ToList();

    Assert.That(hotels, Is.TypeOf<List<Hotel>>());
    Assert.That(hotels.Count, Is.EqualTo(4));
}

如何使此测试工作，使GetListByMatchAsync模拟方法在调用被模拟的GetAllAsync方法之后执行一些逻辑？

Answer 1

首先，您所展示的代码可能无法工作，因为您试图设置的方法不是虚拟的。将要设置的方法声明为虚拟。

第二，这是错误的：

_hotelRepositoryMock.Setup(x => x.GetListByMatchAsync(It.IsAny<string>()));

通过此调用，您可以有效地将GetListByMatchAsync设置为返回Default(Task >) ，即Null。那显然不是你想要的。其中之一：

• 使用.returns(...)指定方法应返回的内容；或，
• 如果方法应该简单地返回基类中的实现将返回的任何内容，请使用.callBase()。（这可能是您需要的。）