给定由不同数量的用户发布的曲目列表当访问者访问“热门曲目”页面时那么以受欢迎程度降序排列曲目

给定两首相同配乐的歌曲当用户转发其中一首歌曲时那么这首歌就会登上“热门曲目”排行榜的榜首



给定两周前发布的两首歌曲，分数略有不同分数最低的曲目会在1周后被转发当分数被计算出来时那么在“热门曲目”页面，显示被转发曲目的排名“上升”

describe("Hot Tracks", () => { it("displays the tracks in descending order of popularity", async () => { const regularTrack = { popularityScore: 1 }; const popularTrack = { popularityScore: 2 }; storeTracks([ regularTrack, popularTrack ]); expect(await getHotTracks()).toMatchObject([ popularTrack, regularTrack ]); });});

const mongodb = require('./mongodb.js');

/* fetch top hot tracks, without processing */const fetchRankedTracks = (params) => mongodb.tracks .find({}, { sort: [['score', 'desc']], ...params }) .toArray();
exports.getHotTracks = async function (params = {}) { const tracks = await fetchRankedTracks(params); const pidList = snip.objArrayToValueArray(tracks, 'pId'); const posts = await fetchPostsByPid(pidList); return tracks.map((track, i) => { const post = posts.find(({ eId }) => eId === track.eId); return computeTrend(post ? mergePostData(track, post) : track); });};

jest.mock("mongodb.js", { tracks: { find: (queryObj, { sort }) => ({ toArray: () => ([ { name: 'track1', score: 1 }, { name: 'track2', score: 2 }, ]), }), },});

async function compareGenres(genre1, genre2) { const tracks1 = await mongodb.tracks.find({ genre: genre1 }).toArray(); const tracks1 = await mongodb.tracks.find({ genre: genre2 }).toArray(); // [...]}

jest.mock("mongodb", { tracks: { find: (queryObj, params) => ({ toArray: () => { if (queryObj === 'rock') { return [ { name: 'track1', score: 1 }, { name: 'track2', score: 2 }, ]; } else if (queryObj === 'hip hop') { return [ { name: 'track3', score: 1 }, { name: 'track4', score: 2 }, ]; } }, }), },});

exports.getHotTracks = async function ( fetchRankedTracks: () => Track[], fetchCorrespondingPosts: (tracks: Track[]) => Post[]) { const tracks = await fetchRankedTracks(); const posts = await fetchCorrespondingPosts(tracks); // [...]

// 注意:在运行这些测试之前，确保MongoDB和Openwhyd服务器正在运行。describe("Hot Tracks (approval tests - to be replaced later by unit tests)", () => { beforeEach(async () => { await mongodb.clearDatabase(); });

 it("renders ranked tracks", async () => { await mongodb.tracks.insertMany([ { name: "a regular track", score: 1 }, { name: "a popular track", score: 2 }, ]); const serverURL = await startOpenwhydServer(); const html = await httpClient.get(`${serverURL}/hot`); expect(html).toMatchSnapshot(); //注意:上面的请求在"tracks"集合=>中做了改变，不需要快照该集合的状态。 });

 it("updates the score of a track when it's reposted", async () => { const users = [ { id: 0, name: "user 0", pwd: "123" }, { id: 1, name: "user 1", pwd: "456" }, ]; await mongodb.users.insertMany(users); const serverURL = await startOpenwhydServer(); const userSession = [ await httpClient.post(`${serverURL}/api/login`, users[0]), await httpClient.post(`${serverURL}/api/login`, users[1]), ]; const posts = [ // user 0 posts track A await httpClient.post( `${serverURL}/api/post`, { action: "insert", eId: "track_A" }, { cookies: userSession[0].cookies } ), // user 0 posts track B await httpClient.post( `${serverURL}/api/post`, { action: "insert", eId: "track_B" }, { cookies: userSession[0].cookies } ),  ]; // user 1 reposts track A await httpClient.post( `${serverURL}/api/post`, { action: "insert", pId: posts[0].pId }, { cookies: userSession[1].cookies } ); const ranking = await httpClient.get(`${serverURL}/hot?format=json`); expect(ranking).toMatchSnapshot(); //注意:上面的请求更新"tracks"集合=>，我们也快照该集合的状态。 const tracksCollection = await mongodb.tracks.find({}).toArray(); expect(tracksCollection).toMatchSnapshot(); });});

 const { _id } = await httpClient.post( `${serverURL}/api/post`, { action: "insert", pId: posts[0].pId }, { cookies: userSession[1].cookies } ); const cleanJSON = (body) => body.replaceAll(_id, '__posted_track_id__'); const ranking = await httpClient.get(`${serverURL}/hot?format=json`); expect(cleanJSON(ranking)).toMatchSnapshot();

describe('hot tracks feature', () => { it('should list one track in first position, if just that track was posted', () => { const postedTrack = { name: 'a good track' }; expect(getHotTracks()).toMatchObject([ postedTrack ]); });});

function getHotTracks() { return [{ name: 'a good track' }];}

function getHotTracks(postedTracks) { // 按分数降序排序 return postedTracks.sort((a, b) => b.score - a.score);}

describe('hot tracks feature', () => { it('should list one track in first position, if just that track was posted', () => { const postedTrack = { name: 'a good track' }; const postedTracks = [ postedTrack ]; expect(getHotTracks(postedTracks)).toMatchObject([ postedTrack ]); });

 it('should list the track with higher score in first position, given two posted tracks with different scores', () => { const regularTrack = { name: 'a good track', score: 1 }; const popularTrack = { name: 'a very good track', score: 2 }; const postedTracks = [ regularTrack, popularTrack ]; expect(getHotTracks(postedTracks)).toMatchObject([ popularTrack, regularTrack ]); });});

function getHotTracks(getTracksByDescendingScore) { return getTracksByDescendingScore();}

describe('hot tracks feature', () => { it('should list one track in first position, if just that track was posted', () => { const postedTrack = { name: 'a good track' }; const getTracksByDescendingScore = () => [ postedTrack ]; expect(getHotTracks(getTracksByDescendingScore)).toMatchObject([ postedTrack ]); });

 it('should list the track with higher score in first position, given two posted tracks with different scores', () => { const regularTrack = { name: 'a good track', score: 1 }; const popularTrack = { name: 'a very good track', score: 2 }; const getTracksByDescendingScore = () => [ regularTrack, popularTrack ]; expect(getHotTracks(getTracksByDescendingScore)).toMatchObject([ popularTrack, regularTrack ]); });});

/* fetch top hot tracks, and include complete post data (from the "post" collection), score, and rank increment */exports.getHotTracksFromDb = async function (params = {}, handler) { const getTracksByDescendingScore = () => exports.fetchRankedTracks(params); const tracks = await getHotTracks(getTracksByDescendingScore); const pidList = snip.objArrayToValueArray(tracks, 'pId'); const posts = await fetchPostsByPid(pidList); // complete track items with additional metadata (from posts) return tracks.map((track) => { const post = posts.find(({ eId }) => eId === track.eId); return computeTrend(post ? mergePostData(track, post) : track); });}

it('should return tracks with post metadata', async () => { const posts = [ { _id: '61e19a3f078b4c9934e72ce4', eId: '1', pl: { name: 'soundtrack of my life', id: 0 }, // metadata from the post that will be included in the list of hot tracks }, { _id: '61e19a3f078b4c9934e72ce5', eId: '2', text: 'my favorite track ever!', // metadata from the post that will be included in the list of hot tracks }, ]; const getTracksByDescendingScore = () => [ { eId: posts[0].eId, pId: posts[0]._id }, { eId: posts[1].eId, pId: posts[1]._id }, ]; const fetchPostsByPid = (pidList) => posts.filter(({ _id }) => pidList.includes(_id)); const hotTracks = await getHotTracks(getTracksByDescendingScore, fetchPostsByPid); expect(hotTracks[0].pl).toMatchObject(posts[0].pl); expect(hotTracks[1].text).toMatchObject(posts[1].text);});

// 文件: app/features/hot-tracks.jsexports.getHotTracks = async function (getTracksByDescendingScore, fetchPostsByPid) { const tracks = await getTracksByDescendingScore(); const pidList = snip.objArrayToValueArray(tracks, 'pId'); const posts = await fetchPostsByPid(pidList); // complete track items with additional metadata (from posts) return tracks.map((track) => { const post = posts.find(({ eId }) => eId === track.eId); return computeTrend(post ? mergePostData(track, post) : track); });};

// 文件: app/models/track.jsexports.getHotTracksFromDb = async function (params = {}, handler) { const getTracksByDescendingScore = () => new Promise((resolve) => { exports.fetch(params, resolve); }); return feature.getHotTracks(getTracksByDescendingScore, fetchPostsByPid);};

it('should list one track in first position, if just that track was posted', async () => { const postedTrack = { name: 'a good track' }; const getTracksByDescendingScore = () => [ postedTrack ]; const fetchPostsByPid = () => []; expect(await getHotTracks(getTracksByDescendingScore, fetchPostsByPid)) .toMatchObject([postedTrack]);});

it('should list the track with higher score in first position, given two posted tracks with different scores', async () => { const regularTrack = { name: 'a good track', score: 1 }; const popularTrack = { name: 'a very good track', score: 2 }; const getTracksByDescendingScore = () => [ popularTrack, regularTrack ]; const fetchPostsByPid = () => []; expect(await getHotTracks(getTracksByDescendingScore, fetchPostsByPid)) .toMatchObject([ popularTrack, regularTrack ]);});

it('should return tracks with post metadata', async () => { const posts = [ { _id: '61e19a3f078b4c9934e72ce4', eId: '1', pl: { name: 'soundtrack of my life', id: 0 }, // metadata from the post that will be included in the list of hot tracks }, { _id: '61e19a3f078b4c9934e72ce5', eId: '2', text: 'my favorite track ever!', // metadata from the post that will be included in the list of hot tracks }, ]; const getTracksByDescendingScore = () => [ { eId: posts[0].eId, pId: posts[0]._id }, { eId: posts[1].eId, pId: posts[1]._id }, ]; const fetchPostsByPid = (pidList) => posts.filter(({ _id }) => pidList.includes(_id)); const hotTracks = await getHotTracks(getTracksByDescendingScore, fetchPostsByPid); expect(hotTracks[0].pl).toMatchObject(posts[0].pl); expect(hotTracks[1].text).toMatchObject(posts[1].text);});