fix(ReplaySubject): don't buffer next if stopped (#5696)

* test(ReplaySubject): add failing tests

* fix(ReplaySubject): don't buffer next if stopped

* chore: remove VSCode-added lodash import

Oh, FFS, now I've done it.

spec/subjects/ReplaySubject-spec.ts

@@ -351,4 +351,32 @@ describe('ReplaySubject', () => {
 
     expect(results).to.deep.equal([3, 4, 5, 'done']);
   });
+
+  it('should not buffer nexted values after complete', () => {
+    const results: (number | string)[] = [];
+    const subject = new ReplaySubject<number>();
+    subject.next(1);
+    subject.next(2);
+    subject.complete();
+    subject.next(3);
+    subject.subscribe({
+      next: value => results.push(value),
+      complete: () => results.push('C'),
+    });
+    expect(results).to.deep.equal([1, 2, 'C']);
+  });
+
+  it('should not buffer nexted values after error', () => {
+    const results: (number | string)[] = [];
+    const subject = new ReplaySubject<number>();
+    subject.next(1);
+    subject.next(2);
+    subject.error(new Error('Boom!'));
+    subject.next(3);
+    subject.subscribe({
+      next: value => results.push(value),
+      error: () => results.push('E'),
+    });
+    expect(results).to.deep.equal([1, 2, 'E']);
+  });
 });

src/internal/ReplaySubject.ts

@@ -65,21 +65,23 @@ export class ReplaySubject<T> extends Subject<T> {
   }
 
   private nextInfiniteTimeWindow(value: T): void {
-    const _events = this._events;
-    _events.push(value);
-    // Since this method is invoked in every next() call than the buffer
-    // can overgrow the max size only by one item
-    if (_events.length > this._bufferSize) {
-      _events.shift();
+    if (!this.isStopped) {
+      const _events = this._events;
+      _events.push(value);
+      // Since this method is invoked in every next() call than the buffer
+      // can overgrow the max size only by one item
+      if (_events.length > this._bufferSize) {
+        _events.shift();
+      }
     }
-
     super.next(value);
   }
 
   private nextTimeWindow(value: T): void {
-    this._events.push({ time: this._getNow(), value });
-    this._trimBufferThenGetEvents();
-
+    if (!this.isStopped) {
+      this._events.push({ time: this._getNow(), value });
+      this._trimBufferThenGetEvents();
+    }
     super.next(value);
   }