[AngularJS] Test an Angular Component with $componentController

Traditionally you had to create DOM elements to test a directive but by shifting our focus to components, writing unit tests got a lot easier using $componentControllerwithin ngMocks. We can now test our component's controller with an easy to use API that does not require us to spin up any DOM elements to do so. In this lesson, we will see how our ES6 tests are transpiled, learn how to test a component using$componentController and talk about how to simulate lifecycle hooks.

Controller:

class CategoriesController {
  constructor(CategoriesModel) {
    'ngInject';

    this.CategoriesModel = CategoriesModel;
  }

  $onInit() {
    this.CategoriesModel.getCategories()
      .then(result => this.categories = result);
  }

  onCategorySelected(category) {
    this.CategoriesModel.setCurrentCategory(category);
  }

  isCurrentCategory(category) {
    return this.CategoriesModel.getCurrentCategory() &&
      this.CategoriesModel.getCurrentCategory().id === category.id;
  }
}

export default CategoriesController;

Test:

import CategoriesModule from './categories';
import CategoriesController from './categories.controller';
import CategoriesComponent from './categories.component';
import CategoriesTemplate from './categories.html';

describe('Categories', () => {
  let component, $componentController, CategoriesModel;

  beforeEach(() => {
    window.module('categories');

    window.module($provide => {
      $provide.value('CategoriesModel', {
        getCategories: () => {
          return {
            then: () => {}
          };
        }
      });
    });
  });

  beforeEach(inject((_$componentController_, _CategoriesModel_) => {
    CategoriesModel = _CategoriesModel_;
    $componentController = _$componentController_;
  }));

  describe('Module', () => {
    it('is named correctly', () => {
      expect(CategoriesModule.name).toEqual('categories');
    });
  });

  describe('Controller', () => {
    it('calls CategoriesModel.getCategories immediately', () => {
      spyOn(CategoriesModel, 'getCategories').and.callThrough();

      component = $componentController('categories', {
        CategoriesModel
      });
      component.$onInit();

      expect(CategoriesModel.getCategories).toHaveBeenCalled();
    });
  });