Why is Mock.Arrange().DoNothing() not available?

[cori]

I'm trying to mock the static System.IO namespace methods in C#, so I have calls like this:

            Mock.SetupStatic<File>();
            Mock.Arrange( () => File.AppendText(Arg.AnyString)).DoNothing();

because I want to stop the filesystem from writing anything.  When I do so, however, I receive the following error:
'Telerik.JustMock.Expectations.FuncExpectation<System.IO.StreamWriter>' does not contain a definition for 'DoNothing' and no extension method 'DoNothing' accepting a first argument of type 'Telerik.JustMock.Expectations.FuncExpectation<System.IO.StreamWriter>' could be found (are you missing a using directive or an assembly reference?)

In a different test method in the same class using a static class of my own, I am able to make that call without any difficulty.

What am I missing?

[Ricky]

Hello Cori,

Thanks for reporting the issue. I tried to mock File.AppendText the following way that works nicely:

[TestMethod]
public void ShouldStopFile_AppendTextForWriting()
{
    Mock.Arrange(() => File.AppendText(Arg.AnyString));
    File.AppendText("anything");
}

Therefore, I found out that DoNothing modifier is not available for members that return a value. But this an optional modifier added to increase readability and without it things should work just fine. But, yes that goes into our product backlog and should be fixed for the next build.

Also, please make sure that you have MockClassAttribute on top of your class which is required for mocking framework members.

Hope this information helps.

Regards,
Mehfuz

[cori]

So is DoNothing() essentially just decoration - in other words, is that the default behavior of Mock.Arrange()?

I suppose that makes sense - if you're mocking a method and you don't tell the mock to do something then be default it will do nothing. Is that the way I should be interpreting this?

[Chris]

Hello Cori,

Yes, exactly, DoNothing is just a decoration method which does nothing but improves readability. Omitting it won't change anything.

Kind regards,
Chris
the Telerik team

[cori]

Perfect, thanks!