karma-runner/karma

Test sharding / parallelization

Open

#439 opened on Mar 29, 2013

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 (43 comments) (88 reactions) (0 assignees)JavaScript (11,918 stars) (1,703 forks)batch import
help wantedtype: feature

Description

Allow splitting a single test suite into multiple chunks, so that it can be executed in multiple browsers and therefore executed on multiple machines or at least using multiple cores.

Contributor guide

Tech stack
javascriptnodejs
Domain
testingperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
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.
needs investigation
Prerequisites
Familiarity with Karma architectureUnderstanding of parallel processing in Node.js
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The issue requests splitting test suites into chunks for parallel execution across multiple browsers or machines. The discussion in comments (43 comments) includes various approaches but no clear consensus or maintainer guidance. To start, examine the Karma test runner source code in the `lib/` directory, particularly the execution flow, to understand current test dispatch. Look at commented suggestions for sharding strategies, such as using environment variables or CLI arguments. There are no linked PRs, so this would require designing and implementing a new feature from scratch.