Moq - 模拟通用存储库

Question

我有一个通用存储库并试图将 .Returns 转换为表达式，但它拒绝...我的代码如下：

public RepositoryTest()
{
    IList<MockObjectSet> mocks = new List<MockObjectSet>()
    {
        new MockObjectSet { FirstName = "Beta", LastName = "Alpha", Mobile = 12345678 },
        new MockObjectSet { FirstName = "Alpha", LastName = "Beta", Mobile = 87654321 }
    };

    var mockRepository = new Mock<IRepository<MockObjectSet>>();

    mockRepository.Setup(x => x.GetBy(It.IsAny<Expression<Func<MockObjectSet, bool>>>()))
        .Returns((Expression<Func<MockObjectSet, bool>> predicate) => mocks.Where(predicate).ToList());

}

只是说

Delegate System.Func<System.Collections.Generic.IEnumerable<expWEBCRM.Tests.Repositories.MockObjectSet>> does not take 1 arguments

提前致谢！

Answer 1

您需要像这样显式指定Returns 重载的类型参数：

mockRepository.Setup(x => x.GetBy(It.IsAny<Expression<Func<MockObjectSet, bool>>>()))
        .Returns<Expression<Func<MockObjectSet, bool>>>(predicate => mocks.Where(predicate).ToList());

EDIT 存储库接受一个表达式并在IQueryable 上使用它。模拟数据源实际上是一个IEnumerable。 LINQ 接口的不同之处在于一个接受 lambda，一个接受一个表达式：

IQueryable<T>.Where(Expression<Func<T,bool>>);
IEnumerable<T>.Where(Func<T,bool>);

在这种情况下发生的情况是尝试用Expression<Func<T,bool>> 调用IEnumerable.Where。解决此问题的最简单方法是将源集合设为IQueryable：

public RepositoryTest()
{
    IQueryable<MockObjectSet> mocks = new List<MockObjectSet>()
    {
        new MockObjectSet { FirstName = "Beta", LastName = "Alpha", Mobile = 12345678 },
        new MockObjectSet { FirstName = "Alpha", LastName = "Beta", Mobile = 87654321 }
    }.AsQueryable();

    var mockRepository = new Mock<IRepository<MockObjectSet>>();

    mockRepository.Setup(x => x.GetBy(It.IsAny<Expression<Func<MockObjectSet, bool>>>()))
        .Returns<Expression<Func<MockObjectSet, bool>>>(predicate => mocks.Where(predicate).ToList());

}