fix(NODE-3305): beforeHandshake flag is always true (#2854)

src/cmap/connection.ts

@@ -281,7 +281,7 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
       if (issue.isTimeout) {
         op.cb(
           new MongoNetworkTimeoutError(`connection ${this.id} to ${this.address} timed out`, {
-            beforeHandshake: !!this[kIsMaster]
+            beforeHandshake: this.ismaster == null
           })
         );
       } else if (issue.isClose) {

src/error.ts

@@ -189,8 +189,8 @@ export class MongoNetworkError extends MongoError {
     super(message);
     this.name = 'MongoNetworkError';
 
-    if (options && options.beforeHandshake === true) {
-      this[kBeforeHandshake] = true;
+    if (options && typeof options.beforeHandshake === 'boolean') {
+      this[kBeforeHandshake] = options.beforeHandshake;
     }
   }
 }

test/unit/cmap/connection.test.js

@@ -5,6 +5,7 @@ const { connect } = require('../../../src/cmap/connect');
 const { Connection } = require('../../../src/cmap/connection');
 const { expect } = require('chai');
 const { ns } = require('../../../src/utils');
+const { getSymbolFrom } = require('../../tools/utils');
 
 describe('Connection - unit/cmap', function () {
   let server;
@@ -58,4 +59,51 @@ describe('Connection - unit/cmap', function () {
       });
     });
   });
+
+  it('should throw a network error with kBeforeHandshake set to false on timeout after hand shake', function (done) {
+    server.setMessageHandler(request => {
+      const doc = request.document;
+      if (doc.ismaster || doc.hello) {
+        request.reply(mock.DEFAULT_ISMASTER_36);
+      }
+      // respond to no other requests to trigger timeout event
+    });
+
+    const options = {
+      hostAddress: server.hostAddress()
+    };
+
+    connect(options, (err, conn) => {
+      expect(err).to.be.a('undefined');
+      expect(conn).to.be.instanceOf(Connection);
+      expect(conn).to.have.property('ismaster').that.is.a('object');
+
+      conn.command(ns('$admin.cmd'), { ping: 1 }, { socketTimeoutMS: 50 }, err => {
+        const beforeHandshakeSymbol = getSymbolFrom(err, 'beforeHandshake', false);
+        expect(beforeHandshakeSymbol).to.be.a('symbol');
+        expect(err).to.have.property(beforeHandshakeSymbol, false);
+
+        done();
+      });
+    });
+  });
+
+  it('should throw a network error with kBeforeHandshake set to true on timeout before hand shake', function (done) {
+    // respond to no requests to trigger timeout event
+    server.setMessageHandler(() => {});
+
+    const options = {
+      hostAddress: server.hostAddress(),
+      socketTimeoutMS: 50
+    };
+
+    connect(options, (err, conn) => {
+      expect(conn).to.be.a('undefined');
+
+      const beforeHandshakeSymbol = getSymbolFrom(err, 'beforeHandshake');
+      expect(err).to.have.property(beforeHandshakeSymbol, true);
+
+      done();
+    });
+  });
 });

test/unit/errors.test.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const expect = require('chai').expect;
+const { getSymbolFrom } = require('../tools/utils');
+const MongoNetworkError = require('../../src/error').MongoNetworkError;
+
+describe('MongoErrors', function () {
+  describe('MongoNetworkError', function () {
+    it('should only define beforeHandshake symbol if boolean option passed in', function () {
+      const errorWithOptionTrue = new MongoNetworkError('', { beforeHandshake: true });
+      expect(getSymbolFrom(errorWithOptionTrue, 'beforeHandshake', false)).to.be.a('symbol');
+
+      const errorWithOptionFalse = new MongoNetworkError('', { beforeHandshake: false });
+      expect(getSymbolFrom(errorWithOptionFalse, 'beforeHandshake', false)).to.be.a('symbol');
+
+      const errorWithBadOption = new MongoNetworkError('', { beforeHandshake: 'not boolean' });
+      expect(getSymbolFrom(errorWithBadOption, 'beforeHandshake', false)).to.be.an('undefined');
+
+      const errorWithoutOption = new MongoNetworkError('');
+      expect(getSymbolFrom(errorWithoutOption, 'beforeHandshake', false)).to.be.an('undefined');
+    });
+  });
+});