我无法在任何地方找到解决方案。这就是我最终解决这个问题的方法。 YMMV，如果您知道更好的方法，请告诉我！
为了提供一些背景信息，这是REST implementation of the Medium.com API 的一部分，我正在作为一个副项目工作。
我是如何嘲笑他们的
- 我对每个链接的方法进行了模拟，并将其设计为返回模型模拟对象本身，以便它可以访问链中的下一个方法。
- 链中的最后一个方法（跳过）旨在返回结果。
- 在测试本身中，我使用 Jest
mockImplementation() 方法为每个测试设计其行为
- 然后可以使用
expect(StoryMock.chainedMethod).toBeCalled[With]() 监视所有这些
const StoryMock = {
getLatestStories, // to be tested
addPagination: jest.fn(), // already tested, can mock
find: jest.fn(() => StoryMock),
sort: jest.fn(() => StoryMock),
limit: jest.fn(() => StoryMock),
skip: jest.fn(() => []),
};
要测试的静态方法定义
/**
* Gets the latest published stories
* - uses limit, currentPage pagination
* - sorted by descending order of publish date
* @param {object} paginationQuery pagination query string params
* @param {number} paginationQuery.limit [10] pagination limit
* @param {number} paginationQuery.currentPage [0] pagination current page
* @returns {object} { stories, pagination } paginated output using Story.addPagination
*/
async function getLatestStories(paginationQuery) {
const { limit = 10, currentPage = 0 } = paginationQuery;
// limit to max of 20 results per page
const limitBy = Math.min(limit, 20);
const skipBy = limitBy * currentPage;
const latestStories = await this
.find({ published: true, parent: null }) // only published stories
.sort({ publishedAt: -1 }) // publish date descending
.limit(limitBy)
.skip(skipBy);
const stories = await Promise.all(latestStories.map(story => story.toResponseShape()));
return this.addPagination({ output: { stories }, limit: limitBy, currentPage });
}
完整的 Jest 测试以查看模拟的实现
const { mocks } = require('../../../../test-utils');
const { getLatestStories } = require('../story-static-queries');
const StoryMock = {
getLatestStories, // to be tested
addPagination: jest.fn(), // already tested, can mock
find: jest.fn(() => StoryMock),
sort: jest.fn(() => StoryMock),
limit: jest.fn(() => StoryMock),
skip: jest.fn(() => []),
};
const storyInstanceMock = (options) => Object.assign(
mocks.storyMock({ ...options }),
{ toResponseShape() { return this; } }, // already tested, can mock
);
describe('Story static query methods', () => {
describe('getLatestStories(): gets the latest published stories', () => {
const stories = Array(20).fill().map(() => storyInstanceMock({}));
describe('no query pagination params: uses default values for limit and currentPage', () => {
const defaultLimit = 10;
const defaultCurrentPage = 0;
const expectedStories = stories.slice(0, defaultLimit);
// define the return value at end of query chain
StoryMock.skip.mockImplementation(() => expectedStories);
// spy on the Story instance toResponseShape() to ensure it is called
const storyToResponseShapeSpy = jest.spyOn(stories[0], 'toResponseShape');
beforeAll(() => StoryMock.getLatestStories({}));
afterAll(() => jest.clearAllMocks());
test('calls find() for only published stories: { published: true, parent: null }', () => {
expect(StoryMock.find).toHaveBeenCalledWith({ published: true, parent: null });
});
test('calls sort() to sort in descending publishedAt order: { publishedAt: -1 }', () => {
expect(StoryMock.sort).toHaveBeenCalledWith({ publishedAt: -1 });
});
test(`calls limit() using default limit: ${defaultLimit}`, () => {
expect(StoryMock.limit).toHaveBeenCalledWith(defaultLimit);
});
test(`calls skip() using <default limit * default currentPage>: ${defaultLimit * defaultCurrentPage}`, () => {
expect(StoryMock.skip).toHaveBeenCalledWith(defaultLimit * defaultCurrentPage);
});
test('calls toResponseShape() on each Story instance found', () => {
expect(storyToResponseShapeSpy).toHaveBeenCalled();
});
test(`calls static addPagination() method with the first ${defaultLimit} stories result: { output: { stories }, limit: ${defaultLimit}, currentPage: ${defaultCurrentPage} }`, () => {
expect(StoryMock.addPagination).toHaveBeenCalledWith({
output: { stories: expectedStories },
limit: defaultLimit,
currentPage: defaultCurrentPage,
});
});
});
describe('with query pagination params', () => {
afterEach(() => jest.clearAllMocks());
test('executes the previously tested behavior using query param values: { limit: 5, currentPage: 2 }', async () => {
const limit = 5;
const currentPage = 2;
const storyToResponseShapeSpy = jest.spyOn(stories[0], 'toResponseShape');
const expectedStories = stories.slice(0, limit);
StoryMock.skip.mockImplementation(() => expectedStories);
await StoryMock.getLatestStories({ limit, currentPage });
expect(StoryMock.find).toHaveBeenCalledWith({ published: true, parent: null });
expect(StoryMock.sort).toHaveBeenCalledWith({ publishedAt: -1 });
expect(StoryMock.limit).toHaveBeenCalledWith(limit);
expect(StoryMock.skip).toHaveBeenCalledWith(limit * currentPage);
expect(storyToResponseShapeSpy).toHaveBeenCalled();
expect(StoryMock.addPagination).toHaveBeenCalledWith({
limit,
currentPage,
output: { stories: expectedStories },
});
});
test('limit value of 500 passed: enforces maximum value of 20 instead', async () => {
const limit = 500;
const maxLimit = 20;
const currentPage = 2;
StoryMock.skip.mockImplementation(() => stories.slice(0, maxLimit));
await StoryMock.getLatestStories({ limit, currentPage });
expect(StoryMock.limit).toHaveBeenCalledWith(maxLimit);
expect(StoryMock.addPagination).toHaveBeenCalledWith({
limit: maxLimit,
currentPage,
output: { stories: stories.slice(0, maxLimit) },
});
});
});
});
});