有没有办法可以在这行代码中模拟 _currencyRepository？

Question

我正在尝试使用 MOQ 框架对一个类进行单元测试。类中的公共方法有如下一行。

看着那条线，我试图模拟 _currencyRepository 但不知道该怎么做。考虑到它有一个像p => new { p.Id, p.Code } 这样的参数。

在分析代码时，它似乎是一种输出 P 的方式 - 我相信匿名方法。

var currencies = await _currencyRepository.GetsAs(p => new { p.Id, p.Code }, p => p.Id == sellCurrencyId || p.Id == buyCurrencyId);

将鼠标悬停在 var 上以了解获取返回的类型，提示显示 IEnumerable<'a> currencies. Anonymous types: 'a is new{Guid Id, string code}。

..而 GetAs 的定义是：

public async Task<IEnumerable<TOutput>> GetsAs<TOutput>(Expression<Func<TEntity, TOutput>> projector,
                                               Expression<Func<TEntity, bool>> spec = null,
                                               Func<IQueryable<TEntity>, IQueryable<TEntity>> preFilter = null,
                                               params Func<IQueryable<TEntity>, IQueryable<TEntity>>[] postFilters)
        {
            if (projector == null)
            {
                throw new ArgumentNullException("projector");
            }

            return await FindCore(true, spec, preFilter, postFilters).Select(projector).ToListAsync();
        }

GetAs() 也是通用类 GenericRepository 中的成员/方法 - 其类定义为：

    public class GenericRepository<TContext, TEntity> : IGenericRepository<TEntity>
        where TEntity : BaseEntity
        where TContext : DbContext
    {
        protected readonly TContext DbContext;
        public GenericRepository(TContext dbContext)
        {
            DbContext = dbContext;
        }

      //followed by method definitions including GetAs
}

上面的类继承自泛型接口IGenericRepository<TEntity>，定义为：

    public interface IGenericRepository<TEntity>
        where TEntity : class
    {
        //list of methods including GetAs
         Task<IEnumerable<TOutput>> GetsAs<TOutput>(Expression<Func<TEntity, TOutput>> projector,
            Expression<Func<TEntity, bool>> spec = null,
            Func<IQueryable<TEntity>, IQueryable<TEntity>> preFilter = null,
            params Func<IQueryable<TEntity>, IQueryable<TEntity>>[] postFilters);

...BaseEntity 只是一个具有属性的类：

    public class BaseEntity
    {
        public BaseEntity()
        {
            Id = Guid.NewGuid();
            CreatedDate = DateTime.Now;
        }
        public Guid Id { get; set; }
        public DateTime CreatedDate { get; set; }
        public DateTime? UpdatedDate { get; set; }
        public Guid? CreatedBy { get; set; }
        public Guid? UpdateddBy { get; set; }

    }

我已经有了要返回的货币列表，只是参数有错误。不确定要使用什么参数匹配器（我知道参数匹配器是 NSubstitute 谈话。不确定在起订量中它是否被称为相同）

我尝试了很多东西。其中之一如下：

            var mockCurrencies3 = new[] { new { Id = buyCurrencyId, Code = "EUR" }, new { Id = sellCurrencyId, Code = "GBP" } };
            MockCurrencyRepository.Setup(x => x.GetsAs(
               It.IsAny<Expression<Func<Currency, (Guid, string)>>>(),
               It.IsAny<Expression<Func<Currency, bool>>>(),
               It.IsAny<Func<IQueryable<Currency>, IQueryable<Currency>>>()))
               .Returns(Task.FromResult(mockCurrencies3.AsEnumerable()));

尝试上述方法不起作用，因为mockCurrencies3 值未在生产代码中返回。我没有得到任何回报。

Answer 1

使用提供的信息，我能够创建一个通用方法来设置所需的行为

[TestClass]
public class MyTestClass {
    [TestMethod]
    public async Task  Should_Mock_Generic() {

        Guid buyCurrencyId = Guid.NewGuid();
        Guid sellCurrencyId = Guid.NewGuid();

        var mockCurrencies3 = new[] { new { Id = buyCurrencyId, Code = "EUR" }, new { Id = sellCurrencyId, Code = "GBP" } };

        var mock = new Mock<IGenericRepository<Currency>>();
        SetupGetAs(mock, mockCurrencies3);

        var _currencyRepository = mock.Object;

        var currencies = await _currencyRepository.GetsAs(p => new { p.Id, p.Code }, p => p.Id == sellCurrencyId || p.Id == buyCurrencyId);

        currencies.Should().NotBeNullOrEmpty();
    }

    Mock<IGenericRepository<TEntity>> SetupGetAs<TEntity, TOutput>(Mock<IGenericRepository<TEntity>> mock, IEnumerable<TOutput> source)
        where TEntity : class {
        mock.Setup(x => x.GetsAs(
          It.IsAny<Expression<Func<TEntity, TOutput>>>(),
          It.IsAny<Expression<Func<TEntity, bool>>>(),
          It.IsAny<Func<IQueryable<TEntity>, IQueryable<TEntity>>>())
       )
       .ReturnsAsync(source);

        return mock;
    }

}