fix(change_stream): do not check isGetMore if error[mongoErrorContext…

…Symbol] is undefined (#1720)

Fixes NODE-1494

lib/change_stream.js

@@ -2,9 +2,7 @@
 
 const EventEmitter = require('events');
 const inherits = require('util').inherits;
-const MongoNetworkError = require('mongodb-core').MongoNetworkError;
-const mongoErrorContextSymbol = require('mongodb-core').mongoErrorContextSymbol;
-const GET_MORE_NON_RESUMABLE_CODES = require('./error_codes').GET_MORE_NON_RESUMABLE_CODES;
+const isResumableError = require('./error').isResumableError;
 
 var cursorOptionNames = ['maxAwaitTimeMS', 'collation', 'readPreference'];
 
@@ -298,35 +296,6 @@ ChangeStream.prototype.stream = function(options) {
   return this.cursor.stream(options);
 };
 
-// From spec@https://github.com/mongodb/specifications/blob/35e466ddf25059cb30e4113de71cdebd3754657f/source/change-streams.rst#resumable-error:
-//
-// An error is considered resumable if it meets any of the following criteria:
-// - any error encountered which is not a server error (e.g. a timeout error or network error)
-// - any server error response from a getMore command excluding those containing the following error codes
-//   - Interrupted: 11601
-//   - CappedPositionLost: 136
-//   - CursorKilled: 237
-// - a server error response with an error message containing the substring "not master" or "node is recovering"
-//
-// An error on an aggregate command is not a resumable error. Only errors on a getMore command may be considered resumable errors.
-
-function isGetMoreError(error) {
-  return !!error[mongoErrorContextSymbol].isGetMore;
-}
-
-function isResumableError(error) {
-  if (!isGetMoreError(error)) {
-    return false;
-  }
-
-  return !!(
-    error instanceof MongoNetworkError ||
-    !GET_MORE_NON_RESUMABLE_CODES.has(error.code) ||
-    error.message.match(/not master/) ||
-    error.message.match(/node is recovering/)
-  );
-}
-
 // Handle new change events. This method brings together the routes from the callback, event emitter, and promise ways of using ChangeStream.
 var processNewChange = function(self, err, change, callback) {
   // Handle errors

lib/error.js

@@ -0,0 +1,43 @@
+'use strict';
+
+const MongoNetworkError = require('mongodb-core').MongoNetworkError;
+const mongoErrorContextSymbol = require('mongodb-core').mongoErrorContextSymbol;
+
+const GET_MORE_NON_RESUMABLE_CODES = new Set([
+  136, // CappedPositionLost
+  237, // CursorKilled
+  11601 // Interrupted
+]);
+
+// From spec@https://github.com/mongodb/specifications/blob/35e466ddf25059cb30e4113de71cdebd3754657f/source/change-streams.rst#resumable-error:
+//
+// An error is considered resumable if it meets any of the following criteria:
+// - any error encountered which is not a server error (e.g. a timeout error or network error)
+// - any server error response from a getMore command excluding those containing the following error codes
+//   - Interrupted: 11601
+//   - CappedPositionLost: 136
+//   - CursorKilled: 237
+// - a server error response with an error message containing the substring "not master" or "node is recovering"
+//
+// An error on an aggregate command is not a resumable error. Only errors on a getMore command may be considered resumable errors.
+
+function isGetMoreError(error) {
+  if (error[mongoErrorContextSymbol]) {
+    return error[mongoErrorContextSymbol].isGetMore;
+  }
+}
+
+function isResumableError(error) {
+  if (!isGetMoreError(error)) {
+    return false;
+  }
+
+  return !!(
+    error instanceof MongoNetworkError ||
+    !GET_MORE_NON_RESUMABLE_CODES.has(error.code) ||
+    error.message.match(/not master/) ||
+    error.message.match(/node is recovering/)
+  );
+}
+
+module.exports = { GET_MORE_NON_RESUMABLE_CODES, isResumableError };

test/unit/change_stream_resume_tests.js

@@ -6,7 +6,8 @@ const MongoClient = require('../../lib/mongo_client');
 const ObjectId = require('../../index').ObjectId;
 const Timestamp = require('../../index').Timestamp;
 const Long = require('../../index').Long;
-const GET_MORE_NON_RESUMABLE_CODES = require('../../lib/error_codes').GET_MORE_NON_RESUMABLE_CODES;
+const GET_MORE_NON_RESUMABLE_CODES = require('../../lib/error').GET_MORE_NON_RESUMABLE_CODES;
+const isResumableError = require('../../lib/error').isResumableError;
 
 describe('Change Stream Resume Tests', function() {
   const test = {};
@@ -126,15 +127,15 @@ describe('Change Stream Resume Tests', function() {
         secondGetMore: req => req.reply(GET_MORE_RESPONSE)
       },
       {
-        description: `should resume on an error that says "not master"`,
+        description: `should resume on an error that says 'not master'`,
         passing: true,
         firstAggregate: req => req.reply(AGGREGATE_RESPONSE),
         secondAggregate: req => req.reply(AGGREGATE_RESPONSE),
         firstGetMore: req => req.reply({ ok: 0, errmsg: 'not master' }),
         secondGetMore: req => req.reply(GET_MORE_RESPONSE)
       },
       {
-        description: `should resume on an error that says "node is recovering"`,
+        description: `should resume on an error that says 'node is recovering'`,
         passing: true,
         firstAggregate: req => req.reply(AGGREGATE_RESPONSE),
         secondAggregate: req => req.reply(AGGREGATE_RESPONSE),
@@ -175,14 +176,17 @@ describe('Change Stream Resume Tests', function() {
       test.server = server;
     });
   });
+
   afterEach(done => changeStream.close(() => client.close(() => mock.cleanup(done))));
 
   configs.forEach(config => {
     it(config.description, {
       metadata: { requires: { mongodb: '>=3.6.0' } },
       test: function() {
         test.server.setMessageHandler(makeServerHandler(config));
-        client = new MongoClient(`mongodb://${test.server.uri()}`, { socketTimeoutMS: 300 });
+        client = new MongoClient(`mongodb://${test.server.uri()}`, {
+          socketTimeoutMS: 300
+        });
         return client
           .connect()
           .then(client => client.db('test'))
@@ -210,3 +214,9 @@ describe('Change Stream Resume Tests', function() {
     });
   });
 });
+
+describe('Change Stream Resume Error Tests', function() {
+  it('should properly process errors that lack the `mongoErrorContextSymbol`', function() {
+    expect(() => isResumableError(new Error())).to.not.throw();
+  });
+});