开玩笑–模拟窗口或文档对象 [英] Jest – Mock Window or Document object

问题描述

如何使用Jest模拟(然后测试)Window或Document对象?尤其是当它具有尚未在文件中定义的嵌套函数时，例如，您正在测试.

How do you mock (and then test) the Window or Document object with Jest? Especially when it has nested functions that may not yet defined in the file you're testing E.g.

const foo = (payload) => {
    window.webkit.messageHandlers.execute.postMessage(payload)
    return true
}

// Jest: TypeError: Cannot read property 'messageHandlers' of undefined'

类似地，您将如何模拟document.location?例如

Similarly, how would you mock document.location? E.g.

const bar = (nonce, payload) => {
    document.location = 'native://somefeature/send?nonce=' + nonce + '&payload=' + payload
    return true
}

我正朝着:

describe('foo', () => {
  it('posts a message', () => {
    const payload = 'payload'
    window.webkit.messageHandlers.execute.postMessage = jest.fn()
    let result = foo(payload) 
    expect(window.webkit.messageHandlers.execute.postMessage).toHaveBeenCalledWith(payload)
  })    
})

我猜您会对document.location =做类似的事情.但是，那当然太简单了，并且不起作用.

I'm guessing you'd do something similar for document.location =. But of course that would be way too easy, and it does not work.

推荐答案

如果还没有找到答案，您应该可以像这样模拟它:

If you haven't found an answer already, you should be able to mock it like this:

  postMessageMock = jest.fn();
  Object.defineProperty(window, 'webkit', {
    value: { messageHandlers: { execute: { postMessage: postMessageMock } } },
  });

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