fix(commands): check doc.cursor errors

Fixes NODE-1528

lib/connection/commands.js

@@ -3,6 +3,7 @@
 var retrieveBSON = require('./utils').retrieveBSON;
 var BSON = retrieveBSON();
 var Long = BSON.Long;
+const MongoError = require('../error').MongoError;
 
 // Incrementing request id
 var _requestId = 0;
@@ -484,6 +485,18 @@ Response.prototype.parse = function(options) {
     // Deserialize but keep the array of documents in non-parsed form
     var doc = this.bson.deserialize(document, _options);
 
+    if (doc instanceof Error) {
+      throw doc;
+    }
+
+    if (doc.errmsg) {
+      throw new MongoError(doc.errmsg);
+    }
+
+    if (!doc.cursor) {
+      throw new MongoError('Cursor not found');
+    }
+
     // Get the documents
     this.documents = doc.cursor[documentsReturnedIn];
     this.numberReturned = this.documents.length;

test/tests/unit/response_test.js

@@ -0,0 +1,66 @@
+'use strict';
+
+const expect = require('chai').expect;
+const MongoError = require('../../../lib/error').MongoError;
+const mock = require('mongodb-mock-server');
+const Server = require('../../../lib/topologies/server');
+const Long = require('bson').Long;
+
+const test = {};
+describe('Response', function() {
+  afterEach(() => mock.cleanup());
+  beforeEach(() => {
+    return mock.createServer().then(mockServer => {
+      test.server = mockServer;
+    });
+  });
+
+  it('should throw when document is error', {
+    metadata: { requires: { topology: ['single'] } },
+    test: function(done) {
+      const errdoc = {
+        errmsg: 'Cursor not found (namespace: "liveearth.entityEvents", id: 2018648316188432590).'
+      };
+
+      const client = new Server(test.server.address());
+
+      test.server.setMessageHandler(request => {
+        const doc = request.document;
+        if (doc.ismaster) {
+          request.reply(
+            Object.assign({}, mock.DEFAULT_ISMASTER, {
+              maxWireVersion: 6
+            })
+          );
+        } else if (doc.find) {
+          request.reply({
+            cursor: {
+              id: Long.fromNumber(1),
+              ns: 'test.test',
+              firstBatch: []
+            },
+            ok: 1
+          });
+        } else if (doc.getMore) {
+          request.reply(errdoc);
+        }
+      });
+
+      client.on('error', done);
+      client.once('connect', () => {
+        const cursor = client.cursor('test.test', { find: 'test' });
+
+        // Execute next
+        cursor.next(function(err) {
+          expect(err).to.exist;
+          expect(err).to.be.instanceof(MongoError);
+          expect(err.message).to.equal(errdoc.errmsg);
+
+          client.destroy();
+          done();
+        });
+      });
+      client.connect();
+    }
+  });
+});