fix(std/async): make pooledMap() errors catchable (#9217)

1 files changed, 26 insertions, 2 deletions

diff --git a/std/async/pool_test.ts b/std/async/pool_test.ts
index 856f4cc0a..81be903ed 100644
--- a/std/async/pool_test.ts
+++ b/std/async/pool_test.ts
@@ -1,6 +1,12 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+import { delay } from "./delay.ts";
 import { pooledMap } from "./pool.ts";
-import { assert } from "../testing/asserts.ts";
+import {
+  assert,
+  assertEquals,
+  assertStringIncludes,
+  assertThrowsAsync,
+} from "../testing/asserts.ts";
 
 Deno.test("[async] pooledMap", async function (): Promise<void> {
   const start = new Date();
@@ -17,4 +23,22 @@ Deno.test("[async] pooledMap", async function (): Promise<void> {
   assert(diff < 3000);
 });
 
-export {};
+Deno.test("[async] pooledMap errors", async function (): Promise<void> {
+  async function mapNumber(n: number): Promise<number> {
+    if (n <= 2) {
+      throw new Error(`Bad number: ${n}`);
+    }
+    await delay(100);
+    return n;
+  }
+  const mappedNumbers: number[] = [];
+  const error = await assertThrowsAsync(async () => {
+    for await (const m of pooledMap(3, [1, 2, 3, 4], mapNumber)) {
+      mappedNumbers.push(m);
+    }
+  }, AggregateError) as AggregateError;
+  assertEquals(mappedNumbers, [3]);
+  assertEquals(error.errors.length, 2);
+  assertStringIncludes(error.errors[0].stack, "Error: Bad number: 1");
+  assertStringIncludes(error.errors[1].stack, "Error: Bad number: 2");
+});