fix(core): Support WiredTiger engine errmsg format in MongoDB 3.2

The new WiredTiger engine is introduced in MongoDB 3.2.
It changes the output errmsg format for violation of unique index.
This commit adds support for the new format.

Fixes meanjs#1245

modules/core/server/controllers/errors.server.controller.js

@@ -7,7 +7,17 @@ var getUniqueErrorMessage = function (err) {
   var output;
 
   try {
-    var fieldName = err.errmsg.substring(err.errmsg.lastIndexOf('.$') + 2, err.errmsg.lastIndexOf('_1'));
+    var begin = 0;
+    if (err.errmsg.lastIndexOf('.$') !== -1) {
+      // support mongodb <= 3.0 (default: MMapv1 engine)
+      // "errmsg" : "E11000 duplicate key error index: mean-dev.users.$email_1 dup key: { : \"[email protected]\" }"
+      begin = err.errmsg.lastIndexOf('.$') + 2;
+    } else {
+      // support mongodb >= 3.2 (default: WiredTiger engine)
+      // "errmsg" : "E11000 duplicate key error collection: mean-dev.users index: email_1 dup key: { : \"[email protected]\" }"
+      begin = err.errmsg.lastIndexOf('index: ') + 7;
+    }
+    var fieldName = err.errmsg.substring(begin, err.errmsg.lastIndexOf('_1'));
     output = fieldName.charAt(0).toUpperCase() + fieldName.slice(1) + ' already exists';
 
   } catch (ex) {

modules/users/tests/server/user.server.routes.tests.js

@@ -742,10 +742,7 @@ describe('User CRUD tests', function () {
               }
 
               // Call the assertion callback
-              // MongoDB changed document validation output in version 3.2:
-              // >= 3.2 11000 duplicate key error collection: mean-test.users index: username already exists
-              // < 3.2 Username already exists
-              userInfoRes.body.message.toLowerCase().should.containEql('username already exists');
+              userInfoRes.body.message.should.equal('Username already exists');
 
               return done();
             });
@@ -797,10 +794,7 @@ describe('User CRUD tests', function () {
               }
 
               // Call the assertion callback
-              // MongoDB changed document validation output in version 3.2:
-              // >= 3.2 11000 duplicate key error collection: mean-test.users index: email already exists
-              // < 3.2 Email already exists
-              userInfoRes.body.message.toLowerCase().should.containEql('email already exists');
+              userInfoRes.body.message.should.equal('Email already exists');
 
               return done();
             });