UnhandledPromiseRejection when I am trying to spy window object (jest nuxt js)-CodePudding

I am using jest to spy window object to define my own window.scrollY value for my nuxt js component.

My jest codes:

const winSpy = jest.spyOn(global, 'window', 'get')
winSpy.mockImplementation(() => ({
  scrollY: 200
}))

It works fine, but the error below is shown in terminal:

node:internal/process/promises:265
        triggerUncaughtException(err, true /* fromPromise */);
        ^

[UnhandledPromiseRejection: This error originated either by throwing inside of an 
async function without a catch block, or by rejecting a promise which was not handled 
with .catch(). The promise rejected with the reason "TypeError: Cannot read 
properties of undefined (reading 'get')".] {

What is the problem?

Can anyone help me to fix that?

CodePudding user response：

You need to include the original window properties in the mockImplementation:

describe('MyComponent', () => {
  it('reads scrollY', () => {
    const originalWindow = { ...window }
    const windowSpy = jest.spyOn(global, 'window', 'get')
    windowSpy.mockImplementation(() => ({
      ...originalWindow,