typescript 使用玩笑模拟时的打字稿错误

Typescript errors when using jest mocks

提问by noblerare

I have a previously-created .jsfile that mocks away some of our functions for jesttest purposes. I'm migrating that to a .tsfile:

我有一个先前创建的.js文件，它模拟了我们的一些功能以进行jest测试。我正在将其迁移到一个.ts文件：

Server.ts

服务器.ts

const Server = jest.genMockFromModule('../Server');

Server.getAsync = Server.default.getAsync;
// other REST-ful functions here

export default Server;

I am getting the following errors:

我收到以下错误：

Property 'getAsync' does not exist on type '{}'

Property 'default' does not exist on type '{}'

类型“{}”上不存在属性“getAsync”

类型“{}”上不存在属性“default”

Then, in a corresponding test file:

然后，在相应的测试文件中：

MyComponent.test.ts

MyComponent.test.ts

import Server from 'path/to/Server';

jest.mock('path/to/Server');

const dispatchMock = jest.fn();
const getStateMock = jest.fn();

describe('MyComponent.someFunction', () => {
    beforeEach(() => {
        jest.resetAllMocks();
    });

    it('Does the right stuff', () => {
        Server.getAsync.mockReturnValueOnce(Promise.resolve([{ key: 'value' }]));
        dispatchMock.mockImplementationOnce((promise) => promise);
        dispatchMock.mockImplementationOnce();

        return someFunction()(dispatchMock)
            .then(() => {
                expect(Server.getAsync).toHaveBeenCalledTimes(1);
                expect(Server.getAsync.mock.calls[0][0]).toBe('something');
            });
    });
});

I am getting errors on dispatchMock.mockImplementationOnce()

我遇到错误 dispatchMock.mockImplementationOnce()

Expected 1 arguments, but got 0. (method) jest.MockInstance<{}>.mockImplementationOnce(fn: (...args: any[]) => any): jest.Mock<{}>

预期 1 个参数，但得到 0。（方法） jest.MockInstance<{}>.mockImplementationOnce(fn: (...args: any[]) => any): jest.Mock<{}>

...on Server.getAsync.mockReturnValueOnce

...在 Server.getAsync.mockReturnValueOnce

Property 'mockReturnValueOnce' does not exist on type '(url: string, baseRoute?: string | null, loadingGenerator?: (isLoading: boolean) => { type: strin...'.

属性 'mockReturnValueOnce' 在类型 '(url: string, baseRoute?: string | null, loadingGenerator?: (isLoading: boolean) => { type: strin...' 上不存在。

...and on Server.getAsync.mock

...等等 Server.getAsync.mock

Property 'mock' does not exist on type '(url: string, baseRoute?: string | null, loadingGenerator?: (isLoading: boolean) => { type: strin...'.

属性 'mock' 在类型 '(url: string, baseRoute?: string | null, loadingGenerator?: (isLoading: boolean) => { type: strin...' 上不存在。

I've been pounding my head on this for a while so any help would be greatly appreciated.

我一直在努力解决这个问题，所以任何帮助都将不胜感激。

UPDATE

更新

Okay, I added as anyto the end of the first line of my Server.tsfile so now it looks like:

好的，我添加as any到Server.ts文件第一行的末尾，现在看起来像：

const Server = jest.genMockFromModule('../Server') as any;

That got rid of the first set of errors. Still facing the errors in my .test.tsfile though.

这消除了第一组错误。尽管如此，仍然面临我的.test.ts文件中的错误。

UPDATE 2

更新 2

I've noticed that when I run the actual jest tests, that they all pass even though there are TypeErrors. These issues don't appear to be related to actual tests.

我注意到，当我运行实际的 jest 测试时，即使存在 TypeErrors，它们也都通过了。这些问题似乎与实际测试无关。

回答by noblerare

I fixed this myself. The way that I got it to work was to cast any calls to Server.getAsyncto the specific jest mock type.

我自己解决了这个问题。我让它工作的方式是将任何调用转换Server.getAsync为特定的 jest 模拟类型。

let getAsyncMock = Server.getAsync as jest.Mock

or

或者

let getAsyncMock = <jest.Mock>(Server.getAsync)

This gets rid of my errors.

这摆脱了我的错误。

回答by iarroyo

Following the @nobleare response... a good update will be to wrap your mock implementation into the beforeAlland clear it into the beforeEachblock:

在@nobleare 响应之后……一个很好的更新是将您的模拟实现包装到 中beforeAll并将其清除到beforeEach块中：

import { AnalyticsApi } from "../../api/src";

jest.mock("../../api/src");

describe('...', () => {

  beforeAll(() => {
    (AnalyticsApi as jest.Mock<AnalyticsApi>).mockImplementation(() => ({
      listPolicies: jest.fn().mockResolvedValue('promiseValue')
    }));
  });

  beforeEach(() => {
    (AnalyticsApi as jest.Mock<AnalyticsApi>).mockClear();
  });

});

回答by Sean Lafferty

To override an import, you can do it like so:

要覆盖导入，您可以这样做：

import { AnalyticsApi } from "../../api/src";

jest.mock("../../api/src");

let listPolicies = jest.fn(() => {
  return Promise.resolve();
});

(AnalyticsApi as jest.Mock<AnalyticsApi>).mockImplementation(() => ({
  listPolicies,
}));

回答by ChristopherStrydom

First of all, you're using genMockFromModulewhich creates a mock of your Serverso there is no need to call jest.mock('path/to/Server');.

首先，您正在使用genMockFromModulewhich 创建了您的模拟，Server因此无需调用jest.mock('path/to/Server');.

Second, what are you trying to achieve by doing Server.getAsync = Server.default.getAsync;? All that does is move the getAsyncup a level which isn't necessary. You could just call jest.genMockFromModule('../Server').default;;

其次，你想通过做Server.getAsync = Server.default.getAsync;什么来实现？所做的只是向上移动getAsync一个不必要的级别。你可以打电话jest.genMockFromModule('../Server').default;;

dispatchMock.mockImplementationOnce()is throwing that error because you said it requires a promise to be passed to it here: dispatchMock.mockImplementationOnce((promise) => promise);

dispatchMock.mockImplementationOnce()正在抛出该错误，因为您说它需要在此处传递给它的承诺： dispatchMock.mockImplementationOnce((promise) => promise);

For Server.getAsync.mockReturnValueOnceand Server.getAsync.mockyou actually want to use mockedinstead of casting the type like the other answers suggest.

对于Server.getAsync.mockReturnValueOnce并且Server.getAsync.mock您实际上想要使用mocked而不是像其他答案建议的那样强制转换类型。

Example: mocked(Server.getAsync).mockReturnValueOnce()

例子： mocked(Server.getAsync).mockReturnValueOnce()

回答by Bohdan Other

Use this

使用这个

import { mocked } from 'ts-jest/utils';
import { foo } from './foo';
jest.mock('./foo');


expect(mocked(foo)).toHaveLength(1);