From 5955556a5b37a5fceb3054a2bd4f80fd665d0efe Mon Sep 17 00:00:00 2001
From: lowlighter <22963968+lowlighter@users.noreply.github.com>
Date: Wed, 21 Jul 2021 20:05:02 +0200
Subject: [PATCH 1/2] fix: assertThrowsAsync always reporting Error instead of
 ErrorClass

---
 testing/asserts.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testing/asserts.ts b/testing/asserts.ts
index fb96a08dacff..5a8adae9282a 100644
--- a/testing/asserts.ts
+++ b/testing/asserts.ts
@@ -641,7 +641,7 @@ export async function assertThrowsAsync<T = void>(
     }
     if (ErrorClass && !(e instanceof ErrorClass)) {
       msg =
-        `Expected error to be instance of "${ErrorClass.name}", but got "${e.name}"${
+        `Expected error to be instance of "${ErrorClass.name}", but was "${e.constructor.name}"${
           msg ? `: ${msg}` : "."
         }`;
       throw new AssertionError(msg);

From 6fae3d8e86f90b562a19015494244006a1f49ad4 Mon Sep 17 00:00:00 2001
From: lowlighter <22963968+lowlighter@users.noreply.github.com>
Date: Sun, 25 Jul 2021 19:51:53 +0200
Subject: [PATCH 2/2] test: add test case

---
 testing/asserts_test.ts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/testing/asserts_test.ts b/testing/asserts_test.ts
index ab22cf805c22..ffda682bb361 100644
--- a/testing/asserts_test.ts
+++ b/testing/asserts_test.ts
@@ -1039,3 +1039,18 @@ Deno.test("Assert Throws Async Parent Error", () => {
     "Fail!",
   );
 });
+
+Deno.test("Assert Throws Async promise rejected with custom Error", async () => {
+  class CustomError extends Error {}
+  class AnotherCustomError extends Error {}
+  await assertThrowsAsync(
+    () =>
+      assertThrowsAsync(
+        () => Promise.reject(new AnotherCustomError("failed")),
+        CustomError,
+        "fail",
+      ),
+    AssertionError,
+    'Expected error to be instance of "CustomError", but was "AnotherCustomError".',
+  );
+});