如何重置一个模块的特定方法与resetAllMocks在Jest?

Question

我为此研究了很长时间，没有一个答案能解决问题。我有resetAllMocksafterEach测试集。我想模拟一个模块的特定方法。

如果我:

import * as ReactRouter from 'react-router';
const mockPush = jest.fn();
jest.mock('react-router', () => ({
...jest.requireActual('react-router'),
useHistory: () => {
return { push: mockPush };
},
useRouteMatch: jest.fn().mockReturnValue({ url: '' })
}));

它在第一个测试用例中工作得很好，但在第二个测试用例中抛出:TypeError: Cannot destructure property 'url' of 'react_router_1.useRouteMatch(...)' as it is undefined.

如果我:

import * as ReactRouter from 'react-router';
const mockPush = jest.fn();
beforeEach(() => {
jest.mock('react-router', () => ({
...jest.requireActual('react-router'),
useHistory: () => {
return { push: mockPush };
},
useRouteMatch: jest.fn().mockReturnValue({ url: '' })
}));
})

它不做任何事情(不模拟值)。

如果我:

import * as ReactRouter from 'react-router';
jest.mock('react-router');
const mockPush = jest.fn();
beforeEach(() => {
jest.spyOn(ReactRouter, 'useHistory').mockReturnValue({ push: mockPush } as any)
jest.spyOn(ReactRouter, 'useRouteMatch').mockReturnValue({ url: '' } as any)
})

它只是不做任何事情(破坏其他功能而不抛出任何错误)。

如果我:

import * as ReactRouter from 'react-router';
const mockPush = jest.fn();
beforeEach(() => {
jest.spyOn(ReactRouter, 'useHistory').mockReturnValue({ push: mockPush } as any)
jest.spyOn(ReactRouter, 'useRouteMatch').mockReturnValue({ url: '' } as any)
})

抛出:TypeError: Cannot redefine property: useHistory at Function.defineProperty (<anonymous>).

不确定在测试后重置所有mock是否如此罕见，因此不需要remock，但我找不到在每次测试前remock的合适解决方案。

Answer 1

最后，我设法通过首先只使用模拟目标方法来解决问题。jest.fn()，并导入jest.requireActual。

然后在beforeEach中执行模拟实现，如:

import * as ReactRouter from 'react-router';
jest.mock('react-router', () => ({
...jest.requireActual('react-router'),
useHistory: jest.fn(),
useRouteMatch: jest.fn()
}));
const mockPush = jest.fn();
beforeEach(() => {
jest.spyOn(ReactRouter, 'useHistory').mockReturnValue({ push: mockPush } as any);
jest.spyOn(ReactRouter, 'useRouteMatch').mockReturnValue({ url: '' } as any);
});