From b8a56bd21b51119971704f6d9f99cd9129679dc6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotr=20B=C5=82a=C5=BCejewicz=20=28Peter=20Blazejewicz=29?=
 <peterblazejewicz@users.noreply.github.com>
Date: Wed, 22 Jan 2020 01:22:54 +0100
Subject: [PATCH] fix(async): correct 'drain' method defs. Closes #41648
 (#41665)

http://caolan.github.io/async/v3/docs.html#cargo
http://caolan.github.io/async/v3/docs.html#QueueObject

Thanks!
---
 types/async/index.d.ts    | 7 ++++++-
 types/async/test/index.ts | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/types/async/index.d.ts b/types/async/index.d.ts
index 54585ddc28..8d7031bff1 100644
--- a/types/async/index.d.ts
+++ b/types/async/index.d.ts
@@ -106,7 +106,12 @@ export interface AsyncCargo {
     push(task: any, callback?: Function): void;
     saturated(): void;
     empty(): void;
-    drain(): void;
+    /**
+     * a function that sets a callback that is called when the last item from the queue has returned from the worker.
+     * If the callback is omitted, q.drain() returns a promise for the next occurrence.
+     */
+    drain(): Promise<void>;
+    drain(handler: () => void): void;
     idle(): boolean;
     pause(): void;
     resume(): void;
diff --git a/types/async/test/index.ts b/types/async/test/index.ts
index 7516e49192..7e3cd35872 100644
--- a/types/async/test/index.ts
+++ b/types/async/test/index.ts
@@ -256,6 +256,8 @@ const cargo = async.cargo((tasks, callback) => {
     }
     callback();
 }, 2);
+cargo.drain(); // $ExpectType Promise<void>
+cargo.drain(() => { console.log('done processing queue'); }); // $ExpectType void
 
 // add some items
 cargo.push({ name: 'foo' }, (err: Error) => { console.log('finished processing foo'); });