chore(assign): replace assign with native Object.assign (#1618)

Part of NODE-1227

lib/collection.js

@@ -20,7 +20,6 @@ var checkCollectionName = require('./utils').checkCollectionName,
   Cursor = require('./cursor'),
   unordered = require('./bulk/unordered'),
   ordered = require('./bulk/ordered'),
-  assign = require('./utils').assign,
   ChangeStream = require('./change_stream'),
   executeOperation = require('./utils').executeOperation;
 
@@ -1375,7 +1374,7 @@ define.classMethod('findOne', { callback: true, promise: true });
  */
 Collection.prototype.rename = function(newName, options, callback) {
   if (typeof options === 'function') (callback = options), (options = {});
-  options = assign({}, options, { readPreference: ReadPreference.PRIMARY });
+  options = Object.assign({}, options, { readPreference: ReadPreference.PRIMARY });
 
   return executeOperation(this.s.topology, rename, [this, newName, options, callback]);
 };
@@ -1579,7 +1578,7 @@ var createIndexes = function(self, indexSpecs, options, callback) {
     }
   }
 
-  options = assign({}, options, { readPreference: ReadPreference.PRIMARY });
+  options = Object.assign({}, options, { readPreference: ReadPreference.PRIMARY });
 
   // Execute the index
   self.s.db.command(
@@ -1996,7 +1995,7 @@ Collection.prototype.indexes = function(options, callback) {
 };
 
 var indexes = function(self, options, callback) {
-  options = assign({}, { full: true }, options);
+  options = Object.assign({}, { full: true }, options);
   self.s.db.indexInformation(self.s.name, options, callback);
 };
 

lib/db.js

@@ -21,7 +21,6 @@ var EventEmitter = require('events').EventEmitter,
   Collection = require('./collection'),
   crypto = require('crypto'),
   mergeOptionsAndWriteConcern = require('./utils').mergeOptionsAndWriteConcern,
-  assign = require('./utils').assign,
   executeOperation = require('./utils').executeOperation;
 
 var debugFields = [
@@ -865,7 +864,7 @@ Db.prototype.dropCollection = function(name, options, callback) {
   decorateWithWriteConcern(cmd, this, options);
 
   // options
-  const opts = assign({}, this.s.options, { readPreference: ReadPreference.PRIMARY });
+  const opts = Object.assign({}, this.s.options, { readPreference: ReadPreference.PRIMARY });
   if (options.session) opts.session = options.session;
 
   return executeOperation(this.s.topology, dropCollection, [this, cmd, opts, callback]);
@@ -905,7 +904,11 @@ Db.prototype.dropDatabase = function(options, callback) {
   decorateWithWriteConcern(cmd, this, options);
 
   // Ensure primary only
-  const finalOptions = assign({}, { readPreference: ReadPreference.PRIMARY }, this.s.options);
+  const finalOptions = Object.assign(
+    {},
+    { readPreference: ReadPreference.PRIMARY },
+    this.s.options
+  );
   if (options.session) {
     finalOptions.session = options.session;
   }

lib/mongo_client.js

@@ -13,7 +13,6 @@ var parse = require('./url_parser'),
   handleCallback = require('./utils').handleCallback,
   Db = require('./db'),
   f = require('util').format,
-  assign = require('./utils').assign,
   shallowClone = require('./utils').shallowClone,
   authenticate = require('./authenticate'),
   ServerSessionPool = require('mongodb-core').Sessions.ServerSessionPool,
@@ -349,7 +348,7 @@ MongoClient.prototype.db = function(dbName, options) {
   options = options || {};
 
   // Copy the options and add out internal override of the not shared flag
-  var finalOptions = assign({}, this.s.options, options);
+  var finalOptions = Object.assign({}, this.s.options, options);
 
   // Do we have the db in the cache already
   if (this.s.dbCache[dbName] && finalOptions.returnNonCachedInstance !== true) {

lib/topologies/mongos.js

@@ -13,8 +13,7 @@ var ServerCapabilities = require('./topology_base').ServerCapabilities,
   MAX_JS_INT = require('../utils').MAX_JS_INT,
   translateOptions = require('../utils').translateOptions,
   filterOptions = require('../utils').filterOptions,
-  mergeOptions = require('../utils').mergeOptions,
-  assign = require('../utils').assign;
+  mergeOptions = require('../utils').mergeOptions;
 
 /**
  * @fileOverview The **Mongos** class is a class that represents a Mongos Proxy topology and is
@@ -214,7 +213,7 @@ class Mongos extends TopologyBase {
     if ('function' === typeof _options) (callback = _options), (_options = {});
     if (_options == null) _options = {};
     if (!('function' === typeof callback)) callback = null;
-    _options = assign({}, this.s.clonedOptions, _options);
+    _options = Object.assign({}, this.s.clonedOptions, _options);
     self.s.options = _options;
 
     // Update bufferMaxEntries

lib/topologies/replset.js

@@ -13,8 +13,7 @@ var Server = require('./server'),
   MAX_JS_INT = require('../utils').MAX_JS_INT,
   translateOptions = require('../utils').translateOptions,
   filterOptions = require('../utils').filterOptions,
-  mergeOptions = require('../utils').mergeOptions,
-  assign = require('../utils').assign;
+  mergeOptions = require('../utils').mergeOptions;
 
 /**
  * @fileOverview The **ReplSet** class is a class that represents a Replicaset topology and is
@@ -241,7 +240,7 @@ class ReplSet extends TopologyBase {
     if ('function' === typeof _options) (callback = _options), (_options = {});
     if (_options == null) _options = {};
     if (!('function' === typeof callback)) callback = null;
-    _options = assign({}, this.s.clonedOptions, _options);
+    _options = Object.assign({}, this.s.clonedOptions, _options);
     self.s.options = _options;
 
     // Update bufferMaxEntries

lib/topologies/server.js

@@ -12,8 +12,7 @@ var CServer = require('mongodb-core').Server,
   MAX_JS_INT = require('../utils').MAX_JS_INT,
   translateOptions = require('../utils').translateOptions,
   filterOptions = require('../utils').filterOptions,
-  mergeOptions = require('../utils').mergeOptions,
-  assign = require('../utils').assign;
+  mergeOptions = require('../utils').mergeOptions;
 
 /**
  * @fileOverview The **Server** class is a class that represents a single server topology and is
@@ -220,7 +219,7 @@ class Server extends TopologyBase {
     if ('function' === typeof _options) (callback = _options), (_options = {});
     if (_options == null) _options = this.s.clonedOptions;
     if (!('function' === typeof callback)) callback = null;
-    _options = assign({}, this.s.clonedOptions, _options);
+    _options = Object.assign({}, this.s.clonedOptions, _options);
     self.s.options = _options;
 
     // Update bufferMaxEntries

lib/utils.js

@@ -312,33 +312,6 @@ var filterOptions = function(options, names) {
   return filterOptions;
 };
 
-// Object.assign method or polyfill
-var assign = Object.assign
-  ? Object.assign
-  : function assign(target) {
-      if (target === undefined || target === null) {
-        throw new TypeError('Cannot convert first argument to object');
-      }
-
-      var to = Object(target);
-      for (var i = 1; i < arguments.length; i++) {
-        var nextSource = arguments[i];
-        if (nextSource === undefined || nextSource === null) {
-          continue;
-        }
-
-        var keysArray = Object.keys(Object(nextSource));
-        for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
-          var nextKey = keysArray[nextIndex];
-          var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
-          if (desc !== undefined && desc.enumerable) {
-            to[nextKey] = nextSource[nextKey];
-          }
-        }
-      }
-      return to;
-    };
-
 // Write concern keys
 var writeConcernKeys = ['w', 'j', 'wtimeout', 'fsync'];
 
@@ -410,7 +383,7 @@ const executeOperation = (topology, operation, args, options) => {
     opOptions = args[args.length - 2];
     if (opOptions == null || opOptions.session == null) {
       session = topology.startSession();
-      assign(args[args.length - 2], { session: session });
+      Object.assign(args[args.length - 2], { session: session });
     } else if (opOptions.session && opOptions.session.hasEnded) {
       throw new MongoError('Use of expired sessions is not permitted');
     }
@@ -475,7 +448,6 @@ exports.decorateCommand = decorateCommand;
 exports.isObject = isObject;
 exports.debugOptions = debugOptions;
 exports.MAX_JS_INT = 0x20000000000000;
-exports.assign = assign;
 exports.mergeOptionsAndWriteConcern = mergeOptionsAndWriteConcern;
 exports.translateReadPreference = translateReadPreference;
 exports.executeOperation = executeOperation;

test/functional/buffering_proxy_tests.js

@@ -2,7 +2,6 @@
 var test = require('./shared').assert;
 var co = require('co');
 var mock = require('../mock');
-var assign = require('../../lib/utils').assign;
 
 var extend = function(template, fields) {
   var object = {};
@@ -38,7 +37,7 @@ describe.skip('Buffering Proxy', function() {
       var electionIds = [new ObjectId(0), new ObjectId(1)];
 
       // Default message fields
-      var defaultFields = assign({}, mock.DEFAULT_ISMASTER, {
+      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
         setName: 'rs',
         setVersion: 1,
         electionId: electionIds[0],
@@ -264,7 +263,7 @@ describe.skip('Buffering Proxy', function() {
       var electionIds = [new ObjectId(0), new ObjectId(1)];
 
       // Default message fields
-      var defaultFields = assign({}, mock.DEFAULT_ISMASTER, {
+      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
         setName: 'rs',
         setVersion: 1,
         electionId: electionIds[0],

test/functional/change_stream_tests.js

@@ -4,7 +4,6 @@ var Transform = require('stream').Transform;
 var MongoNetworkError = require('mongodb-core').MongoNetworkError;
 var setupDatabase = require('./shared').setupDatabase;
 var delay = require('./shared').delay;
-var assign = require('../../lib/utils').assign;
 var co = require('co');
 var mock = require('../mock');
 
@@ -697,7 +696,7 @@ describe('Change Streams', function() {
 
           if (doc.ismaster) {
             request.reply(
-              assign(
+              Object.assign(
                 {
                   ismaster: true,
                   secondary: false,
@@ -801,7 +800,7 @@ describe('Change Streams', function() {
             request.connection.destroy();
           } else if (doc.ismaster) {
             request.reply(
-              assign(
+              Object.assign(
                 {
                   ismaster: true,
                   secondary: false,
@@ -902,7 +901,7 @@ describe('Change Streams', function() {
           // Create a server that responds to the initial aggregation to connect to the server, but not to subsequent getMore requests
           if (doc.ismaster) {
             request.reply(
-              assign(
+              Object.assign(
                 {
                   ismaster: true,
                   secondary: false,
@@ -1338,7 +1337,7 @@ describe('Change Streams', function() {
           // Create a server that responds to the initial aggregation to connect to the server, but not to subsequent getMore requests
           if (doc.ismaster) {
             request.reply(
-              assign(
+              Object.assign(
                 {
                   ismaster: true,
                   secondary: false,