unhandledRejection fails to occur if `.catch()` is used on the last promise

[coreyfarrell]

• Version: 12.13.1 / 13.3.0
• Platform: Linux lt2.cfware.com 5.3.11-200.fc30.x86_64 #1 SMP Tue Nov 12 19:25:25 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Take the following script:

'use strict';

Promise.reject('rejection 1');
Promise.reject('rejection 2').catch(() => {});

The expected result is an unhandledRejection for rejection 1. This script produces no warnings on node.js 12 or 13.

[addaleax]

Something like this might help?

diff --git a/lib/internal/process/promises.js b/lib/internal/process/promises.js
index 35ebb39115f3..7cd40f96cc98 100644
--- a/lib/internal/process/promises.js
+++ b/lib/internal/process/promises.js
@@ -125,7 +125,8 @@ function handledRejection(promise) {
       return;
     }
   }
-  setHasRejectionToWarn(false);
+  if (maybeUnhandledPromises.size === 0 && asyncHandledRejections.length === 0)
+    setHasRejectionToWarn(false);
 }
 
 const unhandledRejectionErrName = 'UnhandledPromiseRejectionWarning';

@nodejs/promises-debugging @joyeecheung (I think this might have come from bf56671)

[joyeecheung]

@addaleax Yeah, that’s likely, as the PR only passed whatever test we had and this does not seem to be tested by us.