From 0d241ba3856d25fb0a4e1732cf61acc6fba54fbb Mon Sep 17 00:00:00 2001
From: Teddy Katz <teddy.katz@gmail.com>
Date: Wed, 28 Mar 2018 01:21:31 -0400
Subject: [PATCH] assert: ensure .rejects() disallows sync throws

This updates `assert.rejects()` to disallow any errors that are thrown
synchronously from the given function. Previously, throwing an error
would cause the same behavior as returning a rejected Promise.

Fixes: https://github.com/nodejs/node/issues/19646
Backport-PR-URL: https://github.com/nodejs/node/pull/24019
PR-URL: https://github.com/nodejs/node/pull/19650
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
---
 lib/assert.js                      |  5 ++++-
 test/parallel/test-assert-async.js | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/lib/assert.js b/lib/assert.js
index 545f76bef4b6a3..594a5acfbde1e3 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -722,8 +722,11 @@ async function waitForActual(block) {
   if (typeof block !== 'function') {
     throw new errors.ERR_INVALID_ARG_TYPE('block', 'Function', block);
   }
+
+  // Return a rejected promise if `block` throws synchronously.
+  const resultPromise = block();
   try {
-    await block();
+    await resultPromise;
   } catch (e) {
     return e;
   }
diff --git a/test/parallel/test-assert-async.js b/test/parallel/test-assert-async.js
index ab03a53cd302c7..c397a4db081d49 100644
--- a/test/parallel/test-assert-async.js
+++ b/test/parallel/test-assert-async.js
@@ -13,7 +13,7 @@ common.crashOnUnhandledRejection();
 
 (async () => {
   await assert.rejects(
-    () => assert.fail(),
+    async () => assert.fail('Failed'),
     common.expectsError({
       code: 'ERR_ASSERTION',
       type: assert.AssertionError,
@@ -57,4 +57,17 @@ common.crashOnUnhandledRejection();
       }
     );
   }
+
+  {
+    const THROWN_ERROR = new Error();
+
+    await assert.rejects(() => {
+      throw THROWN_ERROR;
+    }).then(common.mustNotCall())
+      .catch(
+        common.mustCall((err) => {
+          assert.strictEqual(err, THROWN_ERROR);
+        })
+      );
+  }
 })().then(common.mustCall());