⬆️ Add support for mongodb v4

This change adds support for [`mongodb` v4][1]. The only [change][2]
that seems to affect us is:

 - removal of the top-level `connect()` function

[1]: https://github.com/mongodb/node-mongodb-native/releases/tag/v4.0.0
[2]: https://github.com/mongodb/node-mongodb-native/blob/4.0/docs/CHANGES_4.0.0.md

Author: alecgibson

lib/mongo-milestone-db.js

@@ -1,5 +1,5 @@
 const MilestoneDB = require('sharedb').MilestoneDB;
-const mongodb = require('mongodb');
+const mongodb = require('./mongodb').mongodb;
 
 class MongoMilestoneDB extends MilestoneDB {
   constructor(mongo, options) {
@@ -220,7 +220,9 @@ class MongoMilestoneDB extends MilestoneDB {
       });
     }
 
-    return mongodb.connect(mongo, options);
+    if (typeof mongodb.connect === 'function') return mongodb.connect(mongo, options);
+    const client = new mongodb.MongoClient(mongo, options);
+    return client.connect();
   }
 
   static _snapshotToDbRepresentation(snapshot) {

lib/mongodb.js

@@ -0,0 +1,5 @@
+const mongodb = require('mongodb');
+
+module.exports = {
+  mongodb: mongodb,
+};

package.json

@@ -4,7 +4,7 @@
   "description": "MongoDB milestone snapshot database adapter for ShareDB",
   "main": "lib/index.js",
   "dependencies": {
-    "mongodb": "^2.2.36 || ^3.0.0",
+    "mongodb": "^2.2.36 || ^3.0.0 || ^4.0.0",
     "sharedb": "^1.0.0"
   },
   "devDependencies": {
@@ -14,6 +14,7 @@
     "mocha": "^8.2.1",
     "mongodb2": "npm:mongodb@^2.2.36",
     "mongodb3": "npm:mongodb@^3.0.0",
+    "mongodb4": "npm:mongodb@^4.0.0",
     "nyc": "^15.1.0"
   },
   "scripts": {

test/mongo-milestone-db.js

@@ -2,11 +2,13 @@
 const expect = require('chai').expect;
 const MongoMilestoneDB = require('../lib/mongo-milestone-db');
 const SnapshotFactory = require('./factories/snapshot-factory');
+const mongodbRequire = require('../lib/mongodb');
 
 const MONGO_URL = process.env.TEST_MONGO_URL || 'mongodb://localhost:27017/test';
 
-['mongodb2', 'mongodb3'].forEach((driver) => {
+['mongodb2', 'mongodb3', 'mongodb4'].forEach((driver) => {
   const mongodb = require(driver);
+  mongodbRequire.mongodb = mongodb;
 
   function create(options, callback) {
     if (typeof options === 'function') {
@@ -20,7 +22,13 @@ const MONGO_URL = process.env.TEST_MONGO_URL || 'mongodb://localhost:27017/test'
       mongo: (shareDbCallback) => {
         let mongo;
 
-        mongodb.connect(MONGO_URL)
+        const connect = (url) => {
+          if (typeof mongodb.connect === 'function') return mongodb.connect(url);
+          const client = new mongodb.MongoClient(MONGO_URL);
+          return client.connect();
+        };
+
+        connect(MONGO_URL)
           .then((mongoConnection) => {
             mongo = mongoConnection;
             return MongoMilestoneDB._isLegacyMongoClient(mongo)
@@ -249,7 +257,7 @@ const MONGO_URL = process.env.TEST_MONGO_URL || 'mongodb://localhost:27017/test'
         beforeEach(() => {
           const options = {interval: 100};
           db = new MongoMilestoneDB(MONGO_URL, options);
-          return db._mongoPromise.then(mongo => mongo.db().dropDatabase());
+          return db._db().then(mongo => mongo.dropDatabase());
         });
 
         afterEach((done) => {