Question

11

Verifying function call and inspecting arguments using sinon spies

rated 0 times [ 16] [ 5] / answers: 1 / hits: 59261 / 9 Years ago, wed, april 22, 2015, 12:00:00

I would like to verify that bar() is called inside foo() from my unit test.

I figured that Sinon spies might be suitable, but I don't know how to use them.

Is there any way to check that the method is called? Perhaps even extracting the arguments used in the bar() call?

var spy = sinon.spy(foo);



function foo(){

    bar(1,2,3);

}



function bar(){ }



foo();



// what to do with the spy?

http://jsfiddle.net/8by9jg07/

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answered 9 Years ago sonja · Accepted Answer

In your case, you are trying to see if bar was called, so you want to spy bar rather than foo.

As described in the doc :

function bar(x,y) {

  console.debug(x, y);

}

function foo(z) {

  bar(z, z+1);

}

// Spy on the function bar of the global object.

var spy = sinon.spy(window, bar);



// Now, the bar function has been replaced by a Spy object

// (so this is not necessarily what you want to do) 



foo(1);



bar.getCall(0).args => should be [1,2]

Now, spying on the internals of the function strongly couples your test of foo to its implementation, so you'll fall into the usual mockist vs classical debate.