With Rhino Mocks how to stub a method that makes use of the params keyword?

Question

I am attempting to setup an expectation on a repository. The method makes use of the params keyword:

string GetById(int key, params string[] args);

The expectation I have setup:

var resourceRepo = MockRepository.GenerateMock<IResourceRepository>();
resourceRepo.Expect(r => r.GetById(
    Arg<int>.Is.Equal(123),
    Arg<string>.Is.Equal("Name"),
    Arg<string>.Is.Equal("Super"),
    Arg<string>.Is.Equal("Mario"),
    Arg<string>.Is.Equal("No"),
    Arg<string>.Is.Equal("Yes"),
    Arg<string>.Is.Equal("Maybe")))
    .Return(String.Empty);

throws this exception:

Test method XYZ threw exception: System.InvalidOperationException: Use Arg ONLY within a mock method call while recording. 2 arguments expected, 7 have been defined.

What is wrong with the setup of my expectation?

score 10 · Accepted Answer · edited Jul 10 '12 at 17:17

10

params is just an array:

var resourceRepo = MockRepository.GenerateMock<IResourceRepository>();
resourceRepo
  .Expect(r => r.GetById(
    Arg<int>.Is.Equal(123),
    Arg<string[]>.List.ContainsAll(new[]
                                   {
                                       "Name",
                                       "Super",
                                       "Mario",
                                       "No",
                                       "Yes",
                                       "Maybe"
                                   })))
  .Return(String.Empty);

edited Jul 10 '12 at 17:17

ahsteele

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answered Jul 10 '12 at 05:59

Stefan Steinegger

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Agreed, frustratingly Visual Studio was given me an error when I tried this yesterday. I didn't however actually build the app so the "error" was the IDE "losing its mind." #sigh I made a minor modification to your answer as `ContainsAll` requires an IEnumerable. – ahsteele Jul 10 '12 at 17:16
@ahsteele. Right, it requires an array. Would have been nice to have params there ... – Stefan Steinegger Jul 11 '12 at 05:43
I think the correct answer would be to use `.Equal` instead of `.ContainsAll` there. Contains is not restrictive enough, since it would pass if more things were provided in the original call. – julealgon Feb 13 '14 at 19:10
@julealgon: the question is about the syntax, not about details of the test. Take my code with ContainsAll as an example to write your own test according to your needs. – Stefan Steinegger Feb 14 '14 at 06:30
Ok, fair enough. I thought you were writing his test in the correct form (still seems like it), in which case `Equal` would have to be used. – julealgon Feb 14 '14 at 12:24
I've just come to find this post after having this issue. I came up with a similar solution - except I used a home grown 'SequenceEqual'. HOWEVER I now want to be able to say that say the 1st and 3rd arguments equal x and y, but I don't care what the second argument equals. Any pointers? – Jon H Sep 16 '16 at 15:39

With Rhino Mocks how to stub a method that makes use of the params keyword?

1 Answers1