Not sure how to stub using sinon for qunit

Question

I am trying to unit test method A. All the method does is call method B (which gets urlVars). If the result returned from method A to B is equal to the value passed in to method A then it must return true, else it returns false.

function A(result) {
    if (B()["type"] === result) {
        return true;
    } else {
        return false;
    }
}

function B() {
  do something
  }
  return something;
}

I am trying to make sure function B returns the same value I am passing into function A using sinon. Anyone that can help?

Not sure where to start to be honest, never used sinon or javascript before. — M.Hale

winner_joiner winner_joiner · Accepted Answer · 2016-08-30T12:12:23

The short answer is probably this:

// just for the example
var result = "test";

// function under test
function A(result) {
    if (B()["type"] === result) {
        return true;
    } else {
        return false;
    }
}

//creating the stub
var B = sinon.stub()

// sets the return value of the Stub
B.returns({type:result});

// testing the function
console.info(A(result));

<script src="http://sinonjs.org/releases/sinon-1.17.5.js"></script>

The longer answer is check the documentation http://sinonjs.org/docs/#stubs . The question is do you really need sinonjs, or can you not handcode it?

By unit testing I would always handcode stubs/mocks/... first, and when I start coding to much or duplicating a lot I use a framework.

Update: some info to Unit testing
(I hope this is not too basic, and helps solve your issue)

If I'm testing the A function, I want to know If the function A reacts how I imaging it. So I create testCases

TestCase 1) if I Call Function A with the parameter test the result should be true.

TestCase 2) if I Call Function A with the parameter test1 the result should be false.

... and so on.

Problem: I just want to test the logic from A, without calling B and without relying on the functionality of B
Solution: I mock/stub/... it out.

Here how i would approach it (in a stackoverflow, environment)

var passed = "<span style='color:green'>passed</span><br />";
var failed = "<span style='color:red'>failed</span><br />";
// Helper UnitTesting framework ;-)
function assertIsEqulaHelper(expected, actual){
  document.write(expected===actual?passed:failed);
}

var B;

function testCase1(){
    B = sinon.stub();
    B.onCall(0).returns({type:"test"});
    assertIsEqulaHelper(true, A("test"));
}

function testCase2(){
   B = sinon.stub();
   B.onCall(0).returns({});
  assertIsEqulaHelper(false, A("test1"));
}


// function under test
function A(result) {
  if (B()["type"] === result) {
    return true;
  } else {
    return false;
  }
}

testCase1();
testCase2();

<script src="http://sinonjs.org/releases/sinon-1.17.5.js"></script>

This would have to be optimized, but it can work like this.

Final Update: Information integrated into provided Code

var expected = true;
var returnValue = "something";
var B = sinon.stub();
B.returns({type: returnValue});

//Act
var actual = A(returnValue); //use webm or local

//Assert
deepEqual(actual, expected);

Not sure how to stub using sinon for qunit

1 Answers