NSubstitute ForPartsOf...当调用真正的方法时

Question

我正在尝试使用 ForPartsOf<...>() 替代方法，然后使用 subst.Configure().MyMethod(...).Returns(...) 或 subst.When(x => x.MyMethod(..)).Returns(...)，但在这两种情况下都会调用真正的 MyMethod。我的印象是 Configure() 和 When() 都应该确保 MyMethod() 调用是在 "configure mode" 中进行的，因此不会进行真正的调用。我错了吗？还是我做错了什么？

下面是我的（大大简化并更改了名称的）代码。对于 subst1 和 subst2，真正的 NeedsMoreWork 方法是用 item == null.

调用的

public interface IMyClass
{
    bool NeedsMoreWork(Item item, out Part part);
    bool DoWork(Item item);
}

public class MyClass : IMyClass
{
    private ILogger log;

    public MyClass(ILogger log)
    {
        this.log = log;
    }

    public bool NeedsMoreWork(Item item, out Part part)
    {
        log.Debug($"Examining item {item.Id}");
        part = null;
        if (item.Completed())
        {
            log.Debug($"Item {item.Id} already completed.");
            return false;
        }
        part = item.GetNextPart();
        log.Debug($"Item {item.Id} needs work on part {part.Id}.");
        return true;            
    }

    public bool DoWork(Item item)
    {
        if (!item.NeedsMoreWork(item, out Part part))
            return false;
        log.Debug($"Starting work on part {part.Id}.");
        // Do work on part.
        log.Debug($"Work completed on part {part.Id}.");
        return true;
    }
}

[TestMethod]
public void TestDoWork()
{
    // Version with Configure():
    var subst1 = Substitute.ForPartsOf<MyClass>(Substitute.For<ILogger>());
    subst1.Configure()
        .NeedsMoreWork(Arg.Any<Item>(), out Arg.Any<Part>())
        .Returns(false);

    // Version with WhenForAnyArgs():
    var subst2 = Substitute.ForPartsOf<MyClass>(Substitute.For<ILogger>());
    subst2.WhenForAnyArgs(x => x.NeedsMoreWork(Arg.Any<Item>(), out Arg.Any<Part>())
        .Returns(false);
}

Answer 1

使用 NSubstitute 时，要成为 mocked/stubbed 的成员需要成为 virtual 才能被覆盖。

引用Partial subs and test spies

public class MyClass : IMyClass {
    private readonly ILogger log;

    public MyClass(ILogger log) {
        this.log = log;
    }

    public virtual bool NeedsMoreWork(Item item, out Part part) { //<-- THIS IS NOW VIRTUAL
        log.Debug($"Examining item {item.Id}");
        part = null;
        if (item.Completed()) {
            log.Debug($"Item {item.Id} already completed.");
            return false;
        }
        part = item.GetNextPart();
        log.Debug($"Item {item.Id} needs work on part {part.Id}.");
        return true;            
    }

    public bool DoWork(Item item) {
        if (!NeedsMoreWork(item, out Part part))
            return false;
        log.Debug($"Starting work on part {part.Id}.");
        // Do work on part.
        log.Debug($"Work completed on part {part.Id}.");
        return true;
    }
}

NeedsMoreWork 现在可以根据需要存根

[TestMethod]
public void TestDoWork_Should_Return_False() {
    //Arrange
    var subject = Substitute.ForPartsOf<MyClass>(Substitute.For<ILogger>());
    bool expected = false;
    subject.Configure().NeedsMoreWork(Arg.Any<Item>(), out Arg.Any<Part>()).Returns(expected);

    //Act
    bool actual = subject.DoWork(new Item());

    //Assert - FluentAssertions
    actual.Should().Be(expected);
}

Note the CAUTION comment. If we had not used Configure() here before .NeedsMoreWork(...) then the real method would have executed before we had a chance to override the behavior. In some cases this may not be a problem, but if in doubt make sure you call Configure() first so NSubstitute knows you are configuring a call and don’t want to run any real code. (This still does not guarantee real code will not run – remember, NSubstitute will not prevent non-virtual calls from executing.)

The Configure() method is only available in NSubstitute 4.0 and above. For verisons prior to 4.0 we need to use When .. DoNotCallBase

注意：强调我的

NSubstitute ForPartsOf...当调用真正的方法时

NSubstitute ForPartsOf...When calls real method

c#

mocking

nsubstitute

引用Partial subs and test spies