Stub window properties for Jasmine unit tests

window-props-stub.js

describe('', () => {
  let originalPluginReference;
  let globalPluginStub;
  
  beforeAll(() => {
    // Backing up original property reference, so we could restore it 
    // after all tests being performed
    originalPluginReference = window['GlobalPlugin'];
  });
  
  // We're initializing spy for each test, to avoid each following unit test
  // being dependent on previous one as this makes tests flaky
  beforeEach(() => {
    // Use this property to specify stubbed methods return 
    // values, as you usually do for Spy objects
    globalPluginStub = jasmine.createSpyObj('GlobalPlugin', ['someTestableMethod']);

    Object.defineProperty(window, 'GlobalPlugin', {
      value: globalPluginStub
    });
  });

  afterAll(() => {
    // Restoring original property value after performing all unit tests
    Object.defineProperty(window, 'GlobalPlugin', {
      value: originalPluginReference
    });
  });
});