javascript - JS/JestJS : How to test for a async mocked function?

Question

正如您在我的测试文件中看到的那样，我已经模拟了所有 mongoDB 方法。

现在我需要测试 Content.update() 是否被调用。在此示例代码中，我正在测试一个名为 console.log 的文件，它正在运行，但不是我想要的。我不明白为什么我不能测试 update()

/category.test.js

import { updateCategory } from './category'
import DB from './lib/db'

test('should update document', async () => {
  DB.getDB = jest.fn(
    () => ({
      get: jest.fn(
        () => ({
          findOne: jest.fn(() => ({ some: 'content' })),
          update: jest.fn()
        })
      )
    })
  )
  console.log = jest.fn()

  return updateCategory({}, {
    id: '12345678901234567'
  }).then(() => {
    expect(console.log).toHaveBeenCalled()
    // instead check if `Content.update()` has been called
    expect(DB.getDB().get().update).toHaveBeenCalled() // throws `Expected mock function to have been called.`
  })
})

/category.js

import DB from './lib/db'

export async function updateCategory (obj, { id }) {
  const db = DB.getDB()
  const Content = db.get('content')
  const doc = await Content.findOne({ _id: id })

  console.log('ok');

  await Content.update(
    { _id: id },
    { $set: { category: 'new category' } }
  )
}

Answer 1

将你想要监视的 mock 存储在一个变量中，以便你可以跟踪它:

import { updateCategory } from './category'
import DB from './lib/db'
jest.mock('./lib/db');

const mockUpdate = jest.fn();

test('should update document', async () => {
  DB.getDB.mockImplementation( // <-- available when you call jest.mock above, seems safer than overwriting the implementation in the real import
    () => ({
      get: jest.fn(
        () => ({
          findOne: jest.fn(() => ({ some: 'content' })),
          update: mockUpdate
        })
      )
    })
  )
  console.log = jest.fn()

  return updateCategory({}, {
    id: '12345678901234567'
  }).then(() => {
    expect(console.log).toHaveBeenCalled()
    // instead check if `Content.update()` has been called
    expect(mockUpdate).toHaveBeenCalled() // should work now
  })
})