CODEWITHSUNDEEP
javascriptunit-testingjasmine
FreeFend
FreeFend

Reputation: 202

Testing an objects property change within a spec with karma-jasmine

I'm trying to test a simple object and track its own properties changed by its own methods. Somehow the value of the property isn't changing after launching the methods:

it('extending an object with new properties', function() {
  var newCar = Object.create(car);
  newCar.climatronicOn = false;
  newCar.startClimatronic = function(){
      newCar.climatronicOn = true;
  }
  newCar.stopClimatronic = function(){
      newCar.climatronicOn = false;
  }

  spyOn(newCar, 'startClimatronic');
  spyOn(newCar, 'stopClimatronic');

  // properties
  expect(newCar.hasOwnProperty("climatronicOn")).toBeTruthy();
  expect(typeof newCar.climatronicOn).toEqual("boolean");

  // methods
  expect(newCar.hasOwnProperty("startClimatronic")).toBeTruthy();
  expect(typeof newCar.startClimatronic).toEqual("function");

  expect(newCar.hasOwnProperty("stopClimatronic")).toBeTruthy();
  expect(typeof newCar.stopClimatronic).toEqual("function");

  // running methods
  newCar.startClimatronic();  // should change the newCar.climatronicOn to true
  expect(newCar.startClimatronic).toHaveBeenCalled();             // true
  expect(newCar.climatronicOn).toBeTruthy();  // false, I expected true
  });

I've seen some hints about using getters and setters instead of an object literal and then using spyOnProperty, but I have no idea how to make this up and running when trying to keep the form of newCar.climatronicOn() and newCar.climatronicOff(). How can I check if the methods update the parent objects properties?

My devDependencies from package.json:

"babel-polyfill": "^6.16.0",
"babel-preset-es2015": "^6.24.1",
"babel-preset-es2016": "^6.24.1",
"babel-preset-es2017": "^6.24.1",
"jasmine-core": "^2.5.2",
"karma": "^0.13.20",
"karma-babel-preprocessor": "^6.0.1",
"karma-chrome-launcher": "^0.2.2",
"karma-es6-shim": "^1.0.0",
"karma-firefox-launcher": "^0.1.7",
"karma-ie-launcher": "^0.2.0",
"karma-jasmine": "^0.3.7",
"karma-phantomjs-launcher": "^1.0.0",
"karma-spec-reporter": "0.0.26",
"phantomjs-prebuilt": "^2.1.3",
"run-sequence": "^1.2.2"

Upvotes: 0

Views: 2211

Answers (1)

Castro Roy
Castro Roy

Reputation: 7803

When you spyOn a function( e.g. startClimatronic), and later you call that function(e.g. newCar.startClimatronic();) you are not calling the actual implementation of it and instead of a stubbed jasmine's. So, to make your test success, you need to call .and.callThrough(); on the spy. Something like

spyOn(newCar, 'startClimatronic').and.callThrough();
spyOn(newCar, 'stopClimatronic').and.callThrough();

So, running your tests finished with all success.

Hope it helps

Upvotes: 2

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