如何使用Autofixture创建和填充我的模拟类？

Question

目前我正在使用EF6在UnitOfWork中实现我的存储库.我还创建了一个In-Memory模拟实现(MockUnitOfWork和MockRepository),以便我可以在单元测试中使用它们,但是我现在必须处理对象的繁琐设置.

这不是Autofixture的设计目的吗？我如何获得可以在包含Foo和Barr存储库的测试中使用的MockUnitOfWork ？我正在使用NSubstitute作为我的模拟框架.

IUnitOfWork

public interface IUnitOfWork
{
    void Save();
    void Commit();
    void Rollback();

    IRepository<Foo> FooRepository { get; }
    IRepository<Bar> BarRepository { get; }
}

IRepository

public interface IRepository<TEntity> where TEntity : class
{
    Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null, string         includeProperties = "");

    IEnumerable<TEntity> Get(Expression<Func<TEntity, bool>> filter = null, Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null);
    TEntity GetByID(object id);

    void Insert(TEntity entity);
    void Delete(object id);
    void Delete(TEntity entityToDelete);
    void Update(TEntity entityToUpdate);
}

Answer 1

是的，这正是它的设计目的。请参阅下面的示例。我使用 Mock 而不是 NSubstitute，因为我不熟悉 NSubstitute。您只需要传递另一个自定义，并在设置中使用 NSubstitute 语法。

[SetUp]
public  void SetUp()
{
    // this will make AutoFixture create mocks automatically for all dependencies
    _fixture = new Fixture()
         .Customize(new AutoMoqCustomization()); 

    // whenever AutoFixture needs IUnitOfWork it will use the same  mock object
    // (something like a singleton scope in IOC container)
    _fixture.Freeze<Mock<IUnitOfWork>>(); 

    // suppose YourSystemUnderTest takes IUnitOfWork as dependency,
    // it'll get the one frozen the line above
    _sut = _fixture.Create<YourSystemUnderTest>(); 
}

[Test]
public void SomeTest()
{
    var id = _fixture.Create<object>(); // some random id
    var fooObject = _fixture.Create<Foo>(); // the object repository should return for id

    // setuping THE SAME mock object that wa passed to _sut in SetUp.
    // _fixture.Freeze<Mock part is ESSENTIAL
    // _fixture.Freeze<Mock<IUnitOfWork>>() returns the mock object, so whatever comes
    // next is Mock specific and you'll have to use NSubstitute syntax instead
    _fixture.Freeze<Mock<IUnitOfWork>>()
            .Setup(uow => uow.FooRepository.GetById(id))
            .Returns(fooObject); 

    // if this method will ask the unit of work for FooRepository.GetById(id)
    // it will get fooObject.
    var whatever = _sut.SomeMethod(id); 

    // do assertions
}

AutoFixture 的美妙之处在于，您不必为被测系统的所有依赖项创建模拟。如果您正在测试仅使用一个依赖项的功能，则只需在创建被测系统之前冻结它即可。其余的依赖项将被自动模拟。