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Moq to set up a function return based on called times

Tags:

c#

moq

I need to mock an interface to call to MSMQ, is there a way I can use Moq to simulate real MSMQ scenario that there are 10 messages in the queue, I call mocked function 10 times and I can get a pre-defined object, on 11th time I should get a different return value (e.g. null)?

like image 955
hardywang Avatar asked Jan 16 '13 21:01

hardywang


3 Answers

Moq now has an extension method called SetupSequence() in the Moq namespace which means you can define a distinct return value for each specific call.

The general idea is that that you just chain the return values you need. In the example bellow the first call will return Joe and the second call will return Jane:

customerService
.SetupSequence(s => s.GetCustomerName(It.IsAny<int>()))
.Returns("Joe")   //first call
.Returns("Jane"); //second call

Some more info here.

like image 73
TGH Avatar answered Nov 20 '22 21:11

TGH


I sometimes use a simple counter for such scenarios:

int callCounter = 0;
var mock = new Mock<IWhatever>();
mock.Setup(a => a.SomeMethod())
    .Returns(() => 
    {
       if (callCounter++ < 10)
       {
           // do something
       }
       else
       {
           // do something else
       }
    });
like image 40
Fredrik Mörk Avatar answered Nov 20 '22 21:11

Fredrik Mörk


You can also set up a separate function to do this. You can even pass the function a parameter if you want:

_serviceMock.Setup(x => x.SomeMethod(It.IsAny<String>())).Returns((String param) => getTimesCalled(param));
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Chris - Haddox Technologies Avatar answered Nov 20 '22 19:11

Chris - Haddox Technologies