fix: exhaustAll use exhaustMap to handle synchronous completion of in…

spec/operators/exhaustAll-spec.ts

@@ -287,4 +287,17 @@ describe('exhaust', () => {
 
     expect(sideEffects).to.deep.equal([0, 1, 2]);
   });
+
+  it('should handle synchronously completing inner observables', (done) => {
+    let i = 1;
+    of(of(1), of(2))
+      .pipe(exhaustAll())
+      .subscribe({
+        next: (v) => expect(v).to.equal(i++),
+        complete: () => {
+          expect(i).to.equal(3);
+          done();
+        },
+      });
+  });
 });

src/internal/operators/exhaustAll.ts

@@ -1,8 +1,6 @@
-import { Subscription } from '../Subscription';
 import { OperatorFunction, ObservableInput, ObservedValueOf } from '../types';
-import { operate } from '../util/lift';
-import { innerFrom } from '../observable/innerFrom';
-import { createOperatorSubscriber } from './OperatorSubscriber';
+import { exhaustMap } from './exhaustMap';
+import { identity } from '../util/identity';
 
 /**
  * Converts a higher-order Observable into a first-order Observable by dropping
@@ -49,27 +47,5 @@ import { createOperatorSubscriber } from './OperatorSubscriber';
  * completes before subscribing to the next.
  */
 export function exhaustAll<O extends ObservableInput<any>>(): OperatorFunction<O, ObservedValueOf<O>> {
-  return operate((source, subscriber) => {
-    let isComplete = false;
-    let innerSub: Subscription | null = null;
-    source.subscribe(
-      createOperatorSubscriber(
-        subscriber,
-        (inner) => {
-          if (!innerSub) {
-            innerSub = innerFrom(inner).subscribe(
-              createOperatorSubscriber(subscriber, undefined, () => {
-                innerSub = null;
-                isComplete && subscriber.complete();
-              })
-            );
-          }
-        },
-        () => {
-          isComplete = true;
-          !innerSub && subscriber.complete();
-        }
-      )
-    );
-  });
+  return exhaustMap(identity);
 }