frintjs/frint

Possible race condition issue in `streamProps`

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#382 opened on Nov 28, 2017

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buggood first issuehelp wanted

Description

Current situation

We ship streamProps helper function from frint-component-utils package, which allows combining values from various sources and then generate a single observable of props.

It uses concatMap operator from RxJS internally.

Possible bug

There is a possibility that with concatMap, we will have some race condition issue.

It is advised to use switchMap instead.

What to do

  • Write unit tests proving there is a race condition issue with streamProps
  • If there is, replace concatMap usage with switchMap without breaking the API

Contributor guide

Tech stack
javascript
Domain
frontendtesting
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
RxJSunit testingfrintstreamProps
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
First, locate the `streamProps` function in the `frint component utils` package (likely in a file like `packages/frint component utils/src/streamProps.ts`). Write unit tests that reproduce a race condition scenario by subscribing to multiple observables with delayed emissions. If a race condition is confirmed, replace the internal `concatMap` operator with `switchMap` and ensure existing tests and the API remain intact. Check the existing test suite for guidance.