fix: awaitable isMaster timeout must respect connectTimeoutMS

src/sdam/monitor.ts

@@ -217,7 +217,10 @@ function checkServer(monitor: Monitor, callback: Callback<Document>) {
         : { ismaster: true };
 
     const options = isAwaitable
-      ? { socketTimeout: connectTimeoutMS + maxAwaitTimeMS, exhaustAllowed: true }
+      ? {
+          socketTimeout: connectTimeoutMS ? connectTimeoutMS + maxAwaitTimeMS : 0,
+          exhaustAllowed: true
+        }
       : { socketTimeout: connectTimeoutMS };
 
     if (isAwaitable && monitor[kRTTPinger] == null) {

test/functional/mongo_client_options.test.js

@@ -1,8 +1,9 @@
 'use strict';
-const test = require('./shared').assert,
-  setupDatabase = require('./shared').setupDatabase,
-  expect = require('chai').expect;
+const sinon = require('sinon');
+const { setupDatabase } = require('./shared');
+const { expect } = require('chai');
 const { MongoClient } = require('../../src');
+const { Connection } = require('../../src/cmap/connection');
 
 describe('MongoClient Options', function () {
   before(function () {
@@ -22,11 +23,63 @@ describe('MongoClient Options', function () {
           validateOptions: true
         },
         function (err, client) {
-          test.ok(err.message.indexOf('option notlegal is not supported') !== -1);
+          expect(err)
+            .property('message')
+            .to.match(/option notlegal is not supported/);
           expect(client).to.not.exist;
           done();
         }
       );
     }
   });
+
+  it('must respect an infinite connectTimeoutMS for the streaming protocol', {
+    metadata: { requires: { topology: 'replicaset', mongodb: '>= 4.4' } },
+    test: function (done) {
+      const client = this.configuration.newClient({
+        connectTimeoutMS: 0,
+        heartbeatFrequencyMS: 500
+      });
+      client.connect(err => {
+        expect(err).to.not.exist;
+        const stub = sinon.stub(Connection.prototype, 'command').callsFake(function () {
+          const args = Array.prototype.slice.call(arguments);
+          const ns = args[0];
+          const command = args[1];
+          const options = args[2];
+          if (ns === 'admin.$cmd' && command.ismaster && options.exhaustAllowed) {
+            stub.restore();
+            expect(options).property('socketTimeout').to.equal(0);
+            client.close(done);
+          }
+          stub.wrappedMethod.apply(this, args);
+        });
+      });
+    }
+  });
+
+  it('must respect a finite connectTimeoutMS for the streaming protocol', {
+    metadata: { requires: { topology: 'replicaset', mongodb: '>= 4.4' } },
+    test: function (done) {
+      const client = this.configuration.newClient({
+        connectTimeoutMS: 10,
+        heartbeatFrequencyMS: 500
+      });
+      client.connect(err => {
+        expect(err).to.not.exist;
+        const stub = sinon.stub(Connection.prototype, 'command').callsFake(function () {
+          const args = Array.prototype.slice.call(arguments);
+          const ns = args[0];
+          const command = args[1];
+          const options = args[2];
+          if (ns === 'admin.$cmd' && command.ismaster && options.exhaustAllowed) {
+            stub.restore();
+            expect(options).property('socketTimeout').to.equal(510);
+            client.close(done);
+          }
+          stub.wrappedMethod.apply(this, args);
+        });
+      });
+    }
+  });
 });