You can mock with a spy and import the mocked module. In your test you set how the mock should behave using mockImplementation: jest.mock(‘the-package-to-mock’, () => ({ methodToMock: jest.fn() })); import { methodToMock } from ‘the-package-to-mock’ it(‘test1’, () => { methodToMock.mockImplementation(() => ‘someValue’) }) it(‘test2’, () => { methodToMock.mockImplementation(() => ‘anotherValue’) })
If you think about the responsibility of the AccessDenied component, it isn’t really to send the user home. That’s the overall behaviour you want, but the component’s role in that is simply to send the user to “/”. At the component unit level, therefore, the test could look something like this: import React, { FC … Read more
That issue is caused by many updates inside Component. I got the same issue, this would solve the issue. await act( async () => mount(<App />));
Solution 1: jest.spyOn(Component.methods, ‘METHOD_NAME’) You could use jest.spyOn to mock the component method before mounting: import MyComponent from ‘@/components/MyComponent.vue’ describe(‘MyComponent’, () => { it(‘click does something’, async () => { const mockMethod = jest.spyOn(MyComponent.methods, ‘doSomething’) await shallowMount(MyComponent).find(‘button’).trigger(‘click’) expect(mockMethod).toHaveBeenCalled() }) }) Solution 2: Move methods into separate file that could be mocked The official recommendation is … Read more
Since jest 26, you can use the ‘modern’ fakeTimers implementation (see article here) wich supports the method jest.setSystemTime. beforeAll(() => { jest.useFakeTimers(‘modern’); jest.setSystemTime(new Date(2020, 3, 1)); }); afterAll(() => { jest.useRealTimers(); }); Note that ‘modern’ will be the default implementation from jest version 27. See documentation for setSystemTime here.
The key is using jests spyOn method on the object’s prototype. It should be like this: const spy = jest.spyOn(Component.prototype, ‘methodName’); const wrapper = mount(<Component {…props} />); wrapper.instance().methodName(); expect(spy).toHaveBeenCalled(); As found here e.g.: Test if function is called react and enzyme Please note it is also best practice to clear the spied function after each … Read more
In Jest you have to pass a function into expect(function).toThrow(<blank or type of error>). Example: test(“Test description”, () => { const t = () => { throw new TypeError(); }; expect(t).toThrow(TypeError); }); Or if you also want to check for error message: test(“Test description”, () => { const t = () => { throw new … Read more
The timeout you specify here needs to be shorter than the default timeout. The default timeout is 5000 and the framework by default is jasmine in case of jest. You can specify the timeout inside the test by adding jest.setTimeout(30000); But this would be specific to the test. Or you can set up the configuration … Read more
Use mockFn.mockImplementation(fn). import { funcToMock } from ‘./somewhere’; jest.mock(‘./somewhere’); beforeEach(() => { funcToMock.mockImplementation(() => { /* default implementation */ }); // (funcToMock as jest.Mock)… in TS }); test(‘case that needs a different implementation of funcToMock’, () => { funcToMock.mockImplementation(() => { /* implementation specific to this test */ }); // (funcToMock as jest.Mock)… in TS … Read more
Updated answer: using async / await leads to cleaner code. Old code below. I’ve successfully solved this problem by combining the following elements: Mock out the promise and make it resolve immediately Make the test asynchronous by marking the test function async After simulating the click, wait until the next macrotask to give the promise … Read more