karma-runner/karma

Karma should start a new browser instance when disconnected by a SyntaxError

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#2874 opened on Nov 12, 2017

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 (4 comments) (0 reactions) (0 assignees)JavaScript (11,918 stars) (1,703 forks)batch import
help wanted

Description

Expected behaviour

I would expect that karma would close the current connection and automatically launch another browser instance when it sees another change in the files that it is watching.

HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
  Uncaught SyntaxError: Unexpected identifier
  at event_sequencing.js:52


HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 SUCCESS (0 secs / 0 secs)
HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 5 of 5 SUCCESS (0.012 secs / 0.005 secs)
12 11 2017 08:26:17.933:INFO [watcher]: Changed file "/Users/williamrusnack/Documents/event_sequencing/test.js".

Actual behaviour

Karma instead continues to try and connect to the disconnect browser session when it knows that it has lost the connection.

HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
  Uncaught SyntaxError: Unexpected identifier
  at event_sequencing.js:52


HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 SUCCESS (0 secs / 0 secs)
HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
  Disconnected, because no message in 10000 ms.
HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 DISCONNECTED (10.005 secs / 0 secs)
12 11 2017 08:44:02.222:INFO [watcher]: Changed file "/Users/williamrusnack/Documents/event_sequencing/test.js".
12 11 2017 08:44:02.480:WARN [karma]: No captured browser, open http://localhost:9876/

Environment Details

HeadlessChrome 0.0.0 (Mac OS X 10.11.6) Karma version: 1.7.1

Steps to reproduce the behaviour

Include any syntax error in the javascript test file or the file to be tested that causes the browser to disconnect.

Contributor guide

Tech stack
javascript
Domain
testingdeveloper experience
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
JavaScript knowledgeNode.js basicsFamiliarity with Karma
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate how Karma handles browser disconnection upon syntax error. The key files are likely `lib/browser.js` and `launcher/launcher.js`. The issue reports that after a syntax error, the browser disconnects and Karma does not automatically launch a new browser instance on subsequent file changes. The solution may involve detecting syntax error disconnections and restarting the browser automatically. Review the existing disconnection handling and the file watcher integration to implement the restart logic.