auditTime does not emit last value

[ronag]

Similar to #3351. auditTime does not emit the last value emitted by a completed source.

Looking at the test spec it is not defined if this is the intended behavior or not. However, we've twice encountered this thinking it's very strange behaviour.

> Observable.timer(1000).auditTime(500).subscribe(x => console.log('value', x), undefined, () => console.log('complete')) && null
null
> complete

[benlesh]

audit was, by design, made to audit the last value only at the time of audit, not at time of completion... so to make it do this would be a new feature, which I'm open to discussing, but it's not a bug.

[pbadenski]

Possible duplicate of #1777

[llorenspujol]

I think this feature is interesting for many things.
auditTime is pretty useful for back-pressuring streams, for example a server-data stream. In this use cases you, almost every time, want to get the last value when this stream completes.

Possible solution:
What about using the same configuration options that throttleTime has? config: {leading: boolean, trailing:boolean} with the defaults to {leading: false, trailing: false}. This way auditTime will still work the same way by default and we would have the ability to emit optionally the leading and trailing stream items.

[cartant]

Closing this 'cause, IIRC, the behaviour was changed in v7. See this test:

rxjs/spec/operators/auditTime-spec.ts

Lines 69 to 83 in f3d2e80

	it('should handle a busy producer emitting a regular repeating sequence', () => {
	testScheduler.run(({ hot, time, expectObservable, expectSubscriptions }) => {
	const e1 = hot(' abcdefabcdefabcdefabcdefa|');
	const e1subs = ' ^------------------------!';
	const t = time(' -----| ');
	// -----|
	// -----|
	// -----|
	// -----|
	const expected = '-----f-----f-----f-----f-----(a|)';
	expectObservable(e1.pipe(auditTime(t))).toBe(expected);
	expectSubscriptions(e1.subscriptions).toBe(e1subs);
	});
	});

And this change #5799