Fixed lint errors
diff --git a/src/node/test/credentials_test.js b/src/node/test/credentials_test.js
index 4427e3e..46bb7b7 100644
--- a/src/node/test/credentials_test.js
+++ b/src/node/test/credentials_test.js
@@ -71,7 +71,7 @@
 var fakeFailingGoogleCredentials = {
   getRequestMetadata: function(service_url, callback) {
     setTimeout(function() {
-      callback(new Error("Authorization failure"));
+      callback(new Error('Authorization failure'));
     }, 0);
   }
 };
@@ -219,14 +219,14 @@
     });
   });
   it('Should not add metadata with just SSL credentials', function(done) {
+    // Tests idempotency of credentials composition
     var metadataUpdater = function(service_url, callback) {
       var metadata = new grpc.Metadata();
       metadata.set('plugin_key', 'plugin_value');
       callback(null, metadata);
     };
     var creds = grpc.credentials.createFromMetadataGenerator(metadataUpdater);
-    var combined_creds = grpc.credentials.combineChannelCredentials(
-        client_ssl_creds, creds);
+    grpc.credentials.combineChannelCredentials(client_ssl_creds, creds);
     var client = new Client('localhost:' + port, client_ssl_creds,
                             client_options);
     var call = client.unary({}, function(err, data) {