How to conditionally flush a $timeout in Angular unit test

Question

I have code that is something like this:

function doThing() {
  if (invalidInput) {
    console.error(\'Invalid input.\');
    return;
  }

  $timeout(function()         


        

Answer 1

I suggest define two separate unit tests to verify the behavior of your doThing function. Try following code:

• Controller

(function () {
  'use strict';

  angular.module('myApp', [])
    .controller('MainCtrl', function ($timeout, MyService) {
      var vm = this;

      vm.invalidInput = true;
      vm.doThing = doThing;

      function doThing() {
        if (vm.invalidInput) {
          return;
        }

        $timeout(function () {
          MyService.doThing();
        }, 1000);
      }

    });
})();

• Service

(function () {
  'use strict';

  angular.module('myApp').service('MyService', MyService);

  function MyService() {

    this.doThing = function () {
      // doThing code
    };
  }
})();

• Unit test

'use strict';

describe('Controller: MainCtrl', function () {

  beforeEach(module('myApp'));

  var vm,
    $timeout,
    MyService;

  beforeEach(inject(function (_$controller_, _$timeout_, _MyService_) {
    $timeout = _$timeout_;
    MyService = _MyService_;
    vm = _$controller_('MainCtrl', {
      $timeout: $timeout,
      MyService: MyService
    });
  }));

  it('should call doThing for valid inputs', function () {
    spyOn(MyService, 'doThing').andCallThrough();

    vm.invalidInput = false;
    vm.doThing();
    $timeout.flush();
    expect(MyService.doThing).toHaveBeenCalled();
  });

  it('should not call doThing for invalid inputs', function () {
    spyOn(MyService, 'doThing').andCallThrough();

    vm.invalidInput = true;
    vm.doThing();
    expect(MyService.doThing).not.toHaveBeenCalled();
  });

});

With the first test we expect to call MyService.doThing() function. On other hand, if you have invalidInput as true, the previous function should not be called.

I hope It helps.