How to Write Unit Tests for MongoDB Atlas Functions

1
exports = function() {
2
   return "Hello, world!";
3
};

1
if (typeof module === 'object') {
2
   module.exports = exports;
3
}

1
exports = function (csvTweets) {
2
   csvTweets = csvTweets.replace(/[^a-zA-Z0-9\, "\/\\\n\`~!@#$%^&*()\-_—+=[\]{}|:;\'"<>,.?/']/g, '');
3
   return csvTweets;
4
};
5
6
if (typeof module === 'object') {
7
   module.exports = exports;
8
}

1
const removeBreakingCharacters = require('../../../functions/removeBreakingCharacters/source.js');

1
const { header, validTweetCsv, emojiTweetCsv, emojiTweetCsvClean, specialCharactersTweetCsv } = require('../../constants.js');

1
test('SingleValidTweet', () => {
2
   const csv = header + "\n" + validTweetCsv;
3
   expect(removeBreakingCharacters(csv)).toBe(csv);
4
})

1
test('EmojiTweet', () => {
2
   const csvBefore = header + "\n" + emojiTweetCsv;
3
   const csvAfter = header + "\n" + emojiTweetCsvClean;
4
   expect(removeBreakingCharacters(csvBefore)).toBe(csvAfter);
5
})

1
exports = async function (csvTweets) {
2
   const CSV = require("comma-separated-values");
3
4
   csvTweets = context.functions.execute("removeBreakingCharacters", csvTweets);
5
6
   // Convert the CSV Tweets to JSON Tweets
7
   jsonTweets = new CSV(csvTweets, { header: true }).parse();
8
9
   // Prepare the results object that we will return
10
   var results = {
11
      newTweets: [],
12
      updatedTweets: [],
13
      tweetsNotInsertedOrUpdated: []
14
   }
15
16
   // Clean each Tweet and store it in the DB
17
   jsonTweets.forEach(async (tweet) => {
18
19
      // The Tweet ID from the CSV is being rounded, so we'll manually pull it out of the Tweet link instead
20
      delete tweet["Tweet id"];
21
22
      // Pull the author and Tweet id out of the Tweet permalink
23
      const link = tweet["Tweet permalink"];
24
      const pattern = /https?:\/\/twitter.com\/([^\/]+)\/status\/(.*)/i;
25
      const regexResults = pattern.exec(link);
26
      tweet.author = regexResults[1];
27
      tweet._id = regexResults[2]
28
29
      // Generate a date from the time string
30
      tweet.date = new Date(tweet.time.substring(0, 10));
31
32
      // Upsert the Tweet, so we can update stats for existing Tweets
33
      const result = await context.services.get("mongodb-atlas").db("TwitterStats").collection("stats").updateOne(
34
         { _id: tweet._id },
35
         { $set: tweet },
36
         { upsert: true });
37
38
      if (result.upsertedId) {
39
         results.newTweets.push(tweet._id);
40
      } else if (result.modifiedCount > 0) {
41
         results.updatedTweets.push(tweet._id);
42
      } else {
43
         results.tweetsNotInsertedOrUpdated.push(tweet._id);
44
      }
45
   });
46
   return results;
47
};
48
49
if (typeof module === 'object') {
50
   module.exports = exports;
51
}

1
const storeCsvInDb = require('../../../functions/storeCsvInDb/source.js');
2
3
const { header, validTweetCsv, validTweetJson, validTweetId, validTweet2Csv, validTweet2Id, validTweet2Json, validTweetKenId, validTweetKenCsv, validTweetKenJson } = require('../../constants.js');

1
let updateOne;
2
3
beforeEach(() => {
4
   // Mock functions to support context.services.get().db().collection().updateOne()
5
   updateOne = jest.fn(() => {
6
      return result = {
7
         upsertedId: validTweetId
8
      }
9
   });
10
11
   const collection = jest.fn().mockReturnValue({ updateOne });
12
   const db = jest.fn().mockReturnValue({ collection });
13
   const get = jest.fn().mockReturnValue({ db });
14
15
   collection.updateOne = updateOne;
16
   db.collection = collection;
17
   get.db = db;
18
19
   // Mock the removeBreakingCharacters function to return whatever is passed to it
20
   // Setup global.context.services
21
   global.context = {
22
      functions: {
23
         execute: jest.fn((functionName, csvTweets) => { return csvTweets; })
24
      },
25
      services: {
26
         get
27
      }
28
   }
29
});

1
test('Single tweet', async () => {
2
3
   const csvTweets = header + "\n" + validTweetCsv;
4
5
   expect(await storeCsvInDb(csvTweets)).toStrictEqual({
6
      newTweets: [validTweetId],
7
      tweetsNotInsertedOrUpdated: [],
8
      updatedTweets: []
9
   });
10
11
   expect(context.functions.execute).toHaveBeenCalledWith("removeBreakingCharacters", csvTweets);
12
   expect(context.services.get.db.collection.updateOne).toHaveBeenCalledWith(
13
      { _id: validTweetId },
14
      {
15
         $set: validTweetJson
16
      },
17
      { upsert: true });
18
})