fix(NODE-3986): unskip MONGODB-AWS test (#3397)

Author: biniona-mongodb

src/connection_string.ts

@@ -8,7 +8,12 @@ import { MongoCredentials } from './cmap/auth/mongo_credentials';
 import { AUTH_MECHS_AUTH_SRC_EXTERNAL, AuthMechanism } from './cmap/auth/providers';
 import { Compressor, CompressorName } from './cmap/wire_protocol/compression';
 import { Encrypter } from './encrypter';
-import { MongoAPIError, MongoInvalidArgumentError, MongoParseError } from './error';
+import {
+  MongoAPIError,
+  MongoInvalidArgumentError,
+  MongoMissingCredentialsError,
+  MongoParseError
+} from './error';
 import { Logger, LoggerLevel } from './logger';
 import {
   DriverInfo,
@@ -407,6 +412,12 @@ export function parseOptions(
       });
     }
 
+    if (isAws && mongoOptions.credentials.username && !mongoOptions.credentials.password) {
+      throw new MongoMissingCredentialsError(
+        `When using ${mongoOptions.credentials.mechanism} password must be set when a username is specified`
+      );
+    }
+
     mongoOptions.credentials.validate();
 
     // Check if the only auth related option provided was authSource, if so we can remove credentials

test/unit/assorted/auth.spec.test.ts

@@ -1,19 +1,13 @@
 import { loadSpecTests } from '../../spec';
 import { executeUriValidationTest } from '../../tools/uri_spec_runner';
 
-const SKIP = ['should throw an exception if username and no password (MONGODB-AWS)'];
-
 describe('Auth option spec tests', function () {
   const suites = loadSpecTests('auth');
 
   for (const suite of suites) {
     describe(suite.name, function () {
       for (const test of suite.tests) {
         it(`${test.description}`, function () {
-          if (SKIP.includes(test.description)) {
-            this.test.skipReason = 'NODE-3986: Fix MONGODB-AWS Spec Test';
-            this.skip();
-          }
           executeUriValidationTest(test);
         });
       }