我可以使用 Moq 的 SetupSequence 抛出异常然后返回 void 吗？

Question

I am trying to set up Moq to throw an exception on the first invocation and then return void on the second invocation. The method I'm mocking has a void return type (eg public void Bar() ).

Things I have tried

This has compile errors because Returns requires an argument and SetupSequence requires type arguments.

_mock.SetupSequence(m => m.Bar())
    .Throws<Exception>()
    .Returns();

This has a compile error because Void is not a type in C#.

_mock.SetupSequence<IMyMock, Void>(m => m.Bar())
    .Throws<Exception>() // first invocation throws exception
    .CallBase();

Workaround

In the end I gave up on SetupSequence() and switched to Callback() to throw an exception.

var firstTime = true;
_mock.Setup(m => m.Bar())
    .Callback(() =>
    {
        if (firstTime)
        {
            firstTime = false;
            throw new Exception();
        }
    });

Question

SetupSequence takes a Func , not an Action . Am I correct in assuming that this means SetupSequence() cannot be used to mock void methods?

Answer 1

You can do this starting with Moq 4.8.0:

SetupSequence support for void methods was discussed in GitHub issue #451 and added with GitHub pull request #463 .

You're probably looking for the new .Pass() method:

mock.SetupSequence(m => m.VoidMethod())
    .Throws(new InvalidOperationException())
    .Pass()
    .Pass()
    .Throws(new InvalidOperationException())
    .Pass();

Note that trailing calls to .Pass() are probably unnecessary.