karma-runner/karma

Karma pseudo-reopens PhantomJS connection with asynchronous logging + captureConsole

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#1908 opened on Feb 16, 2016

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help wantedtype: bug

Description

Our frontend code uses Bluebird, which asynchronously logs after tests are run to report unhandled rejections. Looking in Karma's karma.js, it seems these asynchronous logs are just piped down the WebSocket - even if the complete message has already been sent. Karma-side in browser.js, this info event restarts the disconnection timer, despite it having been closed down by the complete handler.

As such, Karma will hang after this happens, and after 10 seconds, a disconnection-due-to-timeout will fire, calling the Karma server's callback a second time (which, in our case, breaks Gulp).

Current workaround is to add captureConsole: false to the Karma client config, though we'd really like to see the logs as well when running via PhantomJS.

Contributor guide

Tech stack
javascriptnodejs
Domain
testingbackend
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.
1-2 days
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
Node.jsJavaScriptAsync programmingWebSocket concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue is caused by asynchronous logging from Bluebird after the 'complete' message is sent. Examine the handling of 'info' events in karma/lib/browser.js and the disconnection timer logic. The fix should ensure that after 'complete', the 'info' event does not restart the timer, or that asynchronous logs are queued until after a safe point. Note the workaround is setting 'captureConsole: false' in Karma client config. The repository is karma runner/karma, and the relevant files are client/karma.js and lib/browser.js.