MemoryStream dragging memory from previous execution

[xtianjohns]

I'm experiencing what seems like odd behavior when working with MemoryStreams and stream completion using xstream.

Consider a stream composed like so:

xs.periodic( 500 ).mapTo( 'world' ).startWith( 'hello' ).take( 2 );

I believe that this stream is a MemoryStream due to the startWith operator. When I add a listener after this stream has completed, the values appear to be emitted in reverse ('world' then 'hello' instead of 'hello' then 'world').

Here is a bin which demonstrates my experience.

I did some sleuthing and considered that since the MemoryStream holds on to the last emitted value, perhaps it was simply holding on to 'world' and then emitting the next known value 'hello', then emitting a maximum of two of those values and terminating. That behavior would make it appear that the stream had somehow been reversed.

Is that behavior expected? I don't really know how to isolate the question further than that - it may not be an issue with MemoryStream, it may be an issue with take, or it may be not an issue at all.

[Hypnosphi]

Seems like the problem is that cleanup method _x is never called in that case for some reasons. It's definitely a bug. https://github.com/staltz/xstream/blob/master/src/core.ts#L1796-L1799

[staltz]

Fixed, released in v5.1.4.

Thanks for the careful report @xtianjohns, and thanks for helping out @Hypnosphi.