process: refactor unhandledRejection logic

This commit prevents a deprecation warning from being emitted
if the unhandledRejection event was actually handled.
PR-URL: #28540Fixes: #28539
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Masashi Hirano <shisama07@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: cjihrig

lib/internal/process/promises.js

@@ -199,10 +199,12 @@ function processPromiseRejections() {
 }
 casekDefaultUnhandledRejections: {
 consthandled=process.emit('unhandledRejection',reason,promise);
-if(!handled)emitUnhandledRejectionWarning(uid,reason);
-if(!deprecationWarned){
-emitDeprecationWarning();
-deprecationWarned=true;
+if(!handled){
+emitUnhandledRejectionWarning(uid,reason);
+if(!deprecationWarned){
+emitDeprecationWarning();
+deprecationWarned=true;
+}
 }
 break;
 }

test/parallel/test-promise-handled-rejection-no-warning.js

@@ -0,0 +1,8 @@
+'use strict';
+constcommon=require('../common');
+
+// This test verifies that DEP0018 does not occur when rejections are handled.
+common.disableCrashOnUnhandledRejection();
+process.on('warning',common.mustNotCall());
+process.on('unhandledRejection',common.mustCall());
+Promise.reject(newError());