From 749bc16cca015c1370b90870fd031d3b7a1bbf4d Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Fri, 14 Jun 2019 10:49:20 +0200
Subject: [PATCH] assert: fix generatedMessage property

This makes sure the `generatedMessage` property is always set as
expected. This was not the case some `assert.throws` and
`assert.rejects` calls.

Backport-PR-URL: https://github.com/nodejs/node/pull/31431
PR-URL: https://github.com/nodejs/node/pull/28263
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/assert.js | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/assert.js b/lib/assert.js
index 025e5bedc02e27..eb74493c443902 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -578,14 +578,21 @@ function expectedException(actual, expected, message, fn) {
       if (expected.test(str))
         return;
 
-      throw new AssertionError({
+      if (!message) {
+        generatedMessage = true;
+        message = 'The input did not match the regular expression ' +
+                  `${inspect(expected)}. Input:\n\n${inspect(str)}\n`;
+      }
+
+      const err = new AssertionError({
         actual,
         expected,
-        message: message || 'The input did not match the regular expression ' +
-                            `${inspect(expected)}. Input:\n\n${inspect(str)}\n`,
+        message,
         operator: fn.name,
         stackStartFn: fn
       });
+      err.generatedMessage = generatedMessage;
+      throw err;
     }
 
     // Handle primitives properly.