jestjs/jest

[Bug]: shard option and global coverageThreshold config

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#12,751 opened on Apr 26, 2022

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:bug: BugHelp WantedPinned

Description

Version

28.0.1

Steps to reproduce

Run tests with the shard option and have coverageThreshold defined in the config with some global values.

Expected behavior

The global values should only be tested against tests who ran in the given shard

Actual behavior

the global values are used for all tests, even those who don't run in the same shard

Additional context

I'm actually not 100% sure about the right behavior to have here. But if we set some global coverage threshold, those won't be met because only a subset of tests run on each shard. All others are considered 0

Environment

System:
    OS: macOS 11.6.4
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 16.14.1 - ~/.volta/tools/image/node/16.14.1/bin/node
    npm: 8.5.0 - ~/.volta/tools/image/node/16.14.1/bin/npm
  npmPackages:
    jest: ^28.0.1 => 28.0.1

Contributor guide

Tech stack
typescriptjavascript
Domain
testing
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.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with JestKnowledge of code coverageUnderstanding of test sharding
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The bug pertains to how global coverage thresholds interact with test sharding. The fix likely requires modifying how Jest aggregates coverage across shards. Relevant files include packages/jest core/src/runJest.ts or packages/jest reporters/src/CoverageReporter.ts. Review the issue comments for further clarification on expected behavior, particularly any maintainer input. Also examine how thresholds are currently applied and where shard information is known.