From 358ae84cb9d59170216e7e0845c192eb3e1dcb51 Mon Sep 17 00:00:00 2001
From: Ben Lesh <ben@benlesh.com>
Date: Mon, 22 Feb 2021 14:22:00 -0600
Subject: [PATCH] fix(buffer): closingNotifier completion does not complete
 resulting observable

Resolves an issue where the resulting observable would complete when the closingNotifier completed. Notifier completion should not complete the result, only source completion should do that.

BREAKING CHANGE: closingNotifier no longer closes the result of `buffer`. If that is truly a desired behavior, then you should use `takeUntil`. Something like: `source$.pipe(buffer(notifier$), takeUntil(notifier$.pipe(ignoreElements(), endWith(true))))`, where `notifier$` is multicast, although there are many ways to compose this behavior.
---
 spec/operators/buffer-spec.ts    |  8 ++++----
 src/internal/operators/buffer.ts | 20 ++++++++++++++------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/spec/operators/buffer-spec.ts b/spec/operators/buffer-spec.ts
index 80ac9a6a0f..243be1b852 100644
--- a/spec/operators/buffer-spec.ts
+++ b/spec/operators/buffer-spec.ts
@@ -49,7 +49,7 @@ describe('Observable.prototype.buffer', () => {
     testScheduler.run(({ hot, expectObservable }) => {
       const a = hot('--1--2--^--3--4--5---6----7--8--9---0---|');
       const b = EMPTY;
-      const expected = '|';
+      const expected = '     --------------------------------|';
       expectObservable(a.pipe(buffer(b))).toBe(expected);
     });
   });
@@ -67,7 +67,7 @@ describe('Observable.prototype.buffer', () => {
     testScheduler.run(({ expectObservable }) => {
       const a = NEVER;
       const b = EMPTY;
-      const expected = '|';
+      const expected = '-';
       expectObservable(a.pipe(buffer(b))).toBe(expected);
     });
   });
@@ -139,9 +139,9 @@ describe('Observable.prototype.buffer', () => {
     // Buffshoulder Boundaries onCompletedBoundaries (RxJS 4)
     testScheduler.run(({ hot, expectObservable, expectSubscriptions }) => {
       const a = hot('--1--2--^--3--4--5---6----7--8--9---0---|');
-      const subs = '         ^----------------!               ';
+      const subs = '         ^-------------------------------!';
       const b = hot('--------^--a-------b---cd|               ');
-      const expected = '     ---a-------b---cd|               ';
+      const expected = '     ---a-------b---cd---------------|';
       const expectedValues = {
         a: ['3'],
         b: ['4', '5'],
diff --git a/src/internal/operators/buffer.ts b/src/internal/operators/buffer.ts
index 56e4015ce0..a9deb9ae81 100644
--- a/src/internal/operators/buffer.ts
+++ b/src/internal/operators/buffer.ts
@@ -1,6 +1,7 @@
 import { Observable } from '../Observable';
 import { OperatorFunction } from '../types';
 import { operate } from '../util/lift';
+import { noop } from '../util/noop';
 import { OperatorSubscriber } from './OperatorSubscriber';
 
 /**
@@ -50,12 +51,19 @@ export function buffer<T>(closingNotifier: Observable<any>): OperatorFunction<T,
 
     // Subscribe to the closing notifier.
     closingNotifier.subscribe(
-      new OperatorSubscriber(subscriber, () => {
-        // Start a new buffer and emit the previous one.
-        const b = currentBuffer;
-        currentBuffer = [];
-        subscriber.next(b);
-      })
+      new OperatorSubscriber(
+        subscriber,
+        () => {
+          // Start a new buffer and emit the previous one.
+          const b = currentBuffer;
+          currentBuffer = [];
+          subscriber.next(b);
+        },
+        // Pass all errors to the consumer.
+        undefined,
+        // Closing notifier should not complete the resulting observable.
+        noop
+      )
     );
 
     return () => {