fix(connection+index): correctly handle setting driver

Author: vkarpov15

lib/connection.js

@@ -7,13 +7,13 @@
 const ChangeStream = require('./cursor/ChangeStream');
 const EventEmitter = require('events').EventEmitter;
 const Schema = require('./schema');
-const Collection = require('./driver').get().Collection;
 const STATES = require('./connectionstate');
 const MongooseError = require('./error/index');
 const SyncIndexesError = require('./error/syncIndexes');
 const PromiseProvider = require('./promise_provider');
 const ServerSelectionError = require('./error/serverSelection');
 const applyPlugins = require('./helpers/schema/applyPlugins');
+const driver = require('./driver');
 const promiseOrCallback = require('./helpers/promiseOrCallback');
 const get = require('./helpers/get');
 const immediate = require('./helpers/immediate');
@@ -1026,6 +1026,7 @@ Connection.prototype.collection = function(name, options) {
   };
   options = Object.assign({}, defaultOptions, options ? utils.clone(options) : {});
   options.$wasForceClosed = this.$wasForceClosed;
+  const Collection = driver.get().Collection;
   if (!(name in this.collections)) {
     this.collections[name] = new Collection(name, this, options);
   }

lib/driver.js

@@ -6,10 +6,20 @@
 
 let driver = null;
 
+const _mongooseInstances = [];
+module.exports._mongooseInstances = _mongooseInstances;
+
 module.exports.get = function() {
   return driver;
 };
 
 module.exports.set = function(v) {
   driver = v;
+
+  for (const mongoose of _mongooseInstances) {
+    const Connection = driver.getConnection();
+    mongoose.Connection = Connection;
+    mongoose.connections = [new Connection(mongoose)];
+    mongoose.Collection = driver.Collection;
+  }
 };

lib/index.js

@@ -70,6 +70,7 @@ function Mongoose(options) {
   }, options);
   const conn = this.createConnection(); // default connection
   conn.models = this.models;
+  driver._mongooseInstances.push(this);
 
   if (this.options.pluralization) {
     this._pluralize = legacyPluralize;
@@ -275,6 +276,7 @@ Mongoose.prototype.get = Mongoose.prototype.set;
 Mongoose.prototype.createConnection = function(uri, options, callback) {
   const _mongoose = this instanceof Mongoose ? this : mongoose;
 
+  const Connection = driver.get().getConnection();
   const conn = new Connection(_mongoose);
   if (typeof options === 'function') {
     callback = options;