Multiple, ordered return values from a stub - possible?

[Erin Swenson-Healey]

Hi all,

I'm curious if there's some way I can do something like:

var myStub = sinon.stub();

myStub.withArgs(1).returns("ham"); // first call
myStub.withArgs(1).returns("sandwich"); // second call, same args

var x = myStub(1); // "ham"
var y = myStub(1); // "sandwich"

I am digging around in the API doc and can't seem to find what I'm
looking for. Any thoughts?

Take care,

Erin

[Christian Johansen]

Hi Erin,

It's not possible today. However, I recently merged a very similar feature for callbacks from Domenic Denicola: https://github.com/cjohansen/Sinon.JS/pull/173

His PR makes it so `yields` called multiple times creates a sequence. I'm open to have the same behavior for `returns` as well, i.e.:

myStub.returns(42).returns(13);

Would make the stub return 42 in the first call and 13 in the second. So, if anyone's up to the task, I'd be happy to review and eventually merge :)

Christian
 

Take care,

Erin

--
MVH
Christian

[Jacob Wan]

I'd like to see such a change, and I can't think of any harm offhand.

In the meantime, in case it helps anyone, what I normally do as a workaround is to have a method wrapping the thing I want to control, such as Math.random, and then I mock that instead.  For example,

(function() {

    test('mocking Math.random', function() {

        function ProductionClass() {}

        ProductionClass.prototype.call_random = function(min, max) {

            if ((undefined === min) || (undefined === max)) {

                return Math.random();

            }

            return Math.random() * (max - min) + min;

        };

        

        // Setup

        var test_me = new ProductionClass,

            mock_test_me = sinon.mock(test_me);

        

        mock_test_me.expects('call_random').withExactArgs(0,10).returns(0);

        mock_test_me.expects('call_random').withExactArgs(0,10).returns(1);

        mock_test_me.expects('call_random').withExactArgs(0,10).returns(2);

        

        // Code under test

        console.log(test_me.call_random(0,10)); // 0

        console.log(test_me.call_random(0,10)); // 1

        console.log(test_me.call_random(0,10)); // 2

        // Assert

        mock_test_me.verify();

    });

}());

Jacob

[Maximilian Antoni]

Hi Jacob,

There is an implementation for this in the code waiting to be released.

It's called "behaviors" and it's going to work like this:

  stub.onFirstCall().returns(1);

  stub.onCall(2).returns(2);

This will also support yields, yieldsTo and throws.

-Max

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[Jacob Wan]

Glad to hear it.  Thanks!