Question

59

Any way to modify Jasmine spies based on arguments?

rated 0 times [ 62] [ 3] / answers: 1 / hits: 138416 / 11 Years ago, wed, april 24, 2013, 12:00:00

I have a function I'd like to test which calls an external API method twice, using different parameters. I'd like to mock this external API out with a Jasmine spy, and return different things based on the parameters. Is there any way to do this in Jasmine? The best I can come up with is a hack using andCallFake:

var functionToTest = function() {

  var userName = externalApi.get('abc');

  var userId = externalApi.get('123');

};





describe('my fn', function() {

  it('gets user name and ID', function() {

    spyOn(externalApi, 'get').andCallFake(function(myParam) {

      if (myParam == 'abc') {

        return 'Jane';

      } else if (myParam == '123') {

        return 98765;

      }

    });

  });

});

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janettejordynm

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answered 11 Years ago daren · Accepted Answer

In Jasmine versions 3.0 and above you can use withArgs

describe('my fn', function() {

  it('gets user name and ID', function() {

    spyOn(externalApi, 'get')

      .withArgs('abc').and.returnValue('Jane')

      .withArgs('123').and.returnValue(98765);

  });

});

For Jasmine versions earlier than 3.0 callFake is the right way to go, but you can simplify it using an object to hold the return values

describe('my fn', function() {

  var params = {

    'abc': 'Jane', 

    '123': 98765

  }



  it('gets user name and ID', function() {

    spyOn(externalApi, 'get').and.callFake(function(myParam) {

     return params[myParam]

    });

  });

});

Depending on the version of Jasmine, the syntax is slightly different:

1.3.1: .andCallFake(fn)

2.0: .and.callFake(fn)

Resources:

withArgs docs

callFake docs

andCallFake vs and.callFake