process: refs --unhandled-rejections documentation in warning message

Refs: #20392

PR-URL: #30564
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Gus Caplan <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: aduh95

lib/internal/process/promises.js

@@ -134,6 +134,9 @@ function emitUnhandledRejectionWarning(uid, reason) {
     'Unhandled promise rejection. This error originated either by ' +
       'throwing inside of an async function without a catch block, ' +
       'or by rejecting a promise which was not handled with .catch(). ' +
+      'To terminate the node process on unhandled promise ' +
+      'rejection, use the CLI flag `--unhandled-rejections=strict` (see ' +
+      'https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). ' +
       `(rejection id: ${uid})`
   );
   try {

test/parallel/test-promises-unhandled-proxy-rejections.js

@@ -12,7 +12,10 @@ const expectedPromiseWarning = ['Unhandled promise rejection. ' +
   'This error originated either by throwing ' +
   'inside of an async function without a catch ' +
   'block, or by rejecting a promise which was ' +
-  'not handled with .catch(). (rejection id: 1)'];
+  'not handled with .catch(). To terminate the ' +
+  'node process on unhandled promise rejection, ' +
+  'use the CLI flag `--unhandled-rejections=strict` (see ' +
+  'https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)'];
 
 function throwErr() {
   throw new Error('Error from proxy');

test/parallel/test-promises-unhandled-symbol-rejections.js

@@ -13,7 +13,10 @@ const expectedPromiseWarning = ['Unhandled promise rejection. ' +
   'This error originated either by throwing ' +
   'inside of an async function without a catch ' +
   'block, or by rejecting a promise which was ' +
-  'not handled with .catch(). (rejection id: 1)'];
+  'not handled with .catch(). To terminate the ' +
+  'node process on unhandled promise rejection, ' +
+  'use the CLI flag `--unhandled-rejections=strict` (see ' +
+  'https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)'];
 
 common.expectWarning({
   DeprecationWarning: expectedDeprecationWarning,