Jest Coverage Comment

A GitHub Action that adds Jest test coverage reports as comments to your pull requests, helping you track and improve test coverage with visual feedback.

🎯 Features

• 📊 Visual Coverage Reports - Automatically comments on PRs with detailed coverage tables
• 🏷️ Coverage Badges - Dynamic badges showing coverage percentage with color coding
• 📈 Test Statistics - Shows passed, failed, skipped tests with execution time via JUnit XML
• 🔗 Direct File Links - Click to view uncovered lines directly in your repository
• 📁 Multiple Reports - Support for monorepo with multiple coverage reports
• 🎨 Customizable - Flexible titles, badges, and display options
• 📝 Multi-Format Support - Works with JSON summary, console output, and JUnit XML
• 🚀 Smart Updates - Updates existing comments instead of creating duplicates

📋 Table of Contents

Click to expand

• Jest Coverage Comment
  • 🎯 Features
  • 📋 Table of Contents
  • 🚀 Quick Start
  • ⚙️ Configuration
    • Inputs
    • Outputs
  • 📚 Usage Examples
    • Basic Usage
    • Complete Configuration
    • Coverage Summary Report
    • Coverage Console Report
    • JUnit Test Report
    • Multiple Files (Monorepo)
    • Matrix Strategy
    • Workflow Dispatch Support
    • Changed Files Only
    • Auto-Update README Badge
  • 🔬 Advanced Features
  • 🎨 Badge Colors
  • 📸 Result Examples
    • Complete Comment Example
    • Text Mode Example
    • Coverage Summary Report
    • Coverage Console Report
    • JUnit Test Report
    • Multiple Files (Monorepo)
  • 🔧 Troubleshooting
    • Comment Not Appearing
    • Coverage Report Too Large
    • Coverage Shows 0%
    • Files Not Found
    • Wrong File Links
    • Workflow Dispatch Events
  • 🤝 Contributing
    • Development Setup
  • 👥 Contributors
  • 📄 License
  • 🔗 Similar Actions

🚀 Quick Start

Add this action to your workflow:

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main

📖 Complete workflow example

name: Jest Coverage Comment
on:
  pull_request:
    branches:
      - '*'

permissions:
  contents: read
  pull-requests: write

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '18'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Run tests with coverage
        run: npx jest --coverage --coverageReporters json-summary

      - name: Jest Coverage Comment
        uses: MishaKav/jest-coverage-comment@main

⚙️ Configuration

Inputs

📝 Core Inputs

Name	Required	Default	Description
github-token	✓	${{github.token}}	GitHub API Access Token
issue-number			Pull request number to comment on (required for workflow_dispatch/workflow_run events)
coverage-summary-path		./coverage/coverage-summary.json	The location of the coverage-summary of Jest
junitxml-path			The location of the junitxml path (npm package jest-junit should be installed)
coverage-path			The location of the coverage.txt (Jest console output)

🎨 Display Options

Name	Default	Description
title		Main title for the comment
summary-title		Title for the coverage summary
badge-title	Coverage	Title for the badge icon
text-instead-badge	false	Use simple text instead of badge images for coverage display
junitxml-title		Title for summary for junitxml
coverage-title	Coverage Report	Title for the coverage report
hide-summary	false	Hide coverage summary report
hide-comment	false	Hide the whole comment (use when you need only the output)
remove-links-to-files	false	Remove links to files (useful when summary-report is too big)
remove-links-to-lines	false	Remove links to lines (useful when summary-report is too big)

🔧 Advanced Options

Name	Default	Description
create-new-comment	false	When false, will update the same comment, otherwise will publish new comment on each run
unique-id-for-comment		When running in a matrix, pass the matrix value, so each comment will be updated its own comment
coverage-path-prefix		Prefix for path when link to files in comment
report-only-changed-files	false	Show in report only changed files for this commit, and not all files
multiple-files		You can pass array of json-summary.json files and generate single comment with table of results Single line should look like Title1, ./path/to/json-summary.json
multiple-junitxml-files		You can pass array of junit.xml files and generate single comment with table of results Single line should look like Title1, ./path/to/junit.xml

Outputs

📤 Available Outputs

Name	Example	Description
coverage	78	Percentage of the coverage, get from coverage-summary.json
color	yellow	Color of the percentage. You can see the whole list of badge colors
summaryHtml	...	Markdown table with summary. See the result examples
tests	9	Total number of tests, get from junitxml
skipped	0	Total number of skipped tests, get from junitxml
failures	0	Total number of tests with failures, get from junitxml
errors	0	Total number of tests with errors, get from junitxml
time	2.883	Seconds that took to run all the tests, get from junitxml
lines	71	Lines covered, get from Jest text report
branches	100	Branches covered, get from Jest text report
functions	28	Functions covered, get from Jest text report
statements	100	Statements covered, get from Jest text report

📚 Usage Examples

Basic Usage

Standard PR Comment

name: Jest Coverage Comment
on:
  pull_request:
jobs:
  coverage:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Install dependencies
        run: npm ci
      - name: Run tests with coverage
        run: npx jest --coverage --coverageReporters json-summary
      - name: Jest Coverage Comment
        uses: MishaKav/jest-coverage-comment@main

This will create a comment showing coverage percentage with a badge and summary table.

Complete Configuration

Example showing all available parameters

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    github-token: ${{ secrets.GITHUB_TOKEN }}
    coverage-summary-path: ./coverage/coverage-summary.json
    title: My Jest Coverage Comment
    summary-title: My Summary Title
    badge-title: Coverage
    text-instead-badge: false
    hide-comment: false
    create-new-comment: false
    hide-summary: false
    remove-links-to-files: false
    remove-links-to-lines: false
    junitxml-title: My JUnit Title
    junitxml-path: ./coverage/junit.xml
    coverage-title: My Coverage Title
    coverage-path: ./coverage.txt
    coverage-path-prefix: src/
    report-only-changed-files: false

Coverage Summary Report

Generate summary from JSON coverage report

Configure Jest to generate JSON summary:

// jest.config.js
module.exports = {
  collectCoverage: true,
  coverageReporters: ['json-summary', 'text', 'html'],
  coverageDirectory: 'coverage',
}

Workflow:

- name: Run tests
  run: npx jest --coverage

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    coverage-summary-path: ./coverage/coverage-summary.json

Output: Badge with coverage percentage and summary table showing file-by-file coverage.

Coverage Console Report

Generate report from Jest console output with file links

- name: Run tests
  run: npx jest --coverage | tee ./coverage.txt && exit ${PIPESTATUS[0]}

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    coverage-path: ./coverage.txt
    coverage-title: Detailed Coverage Report

Output: Expandable section with detailed coverage report, including clickable links to files and specific uncovered lines.

JUnit Test Report

Add test results with jest-junit package

Install jest-junit:

npm install --save-dev jest-junit

Configure Jest:

// jest.config.js
module.exports = {
  reporters: [
    'default',
    ['jest-junit', { outputDirectory: 'coverage', outputName: 'junit.xml' }],
  ],
}

Workflow:

- name: Run tests
  run: npx jest --coverage

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    junitxml-path: ./coverage/junit.xml
    junitxml-title: Test Results

Output: Table showing tests count, skipped, failures, errors, and execution time.

Multiple Files (Monorepo)

Generate combined report for multiple packages

- name: Run tests for all packages
  run: |
    cd packages/frontend && npm test -- --coverage --coverageDirectory ../../coverage/frontend
    cd packages/backend && npm test -- --coverage --coverageDirectory ../../coverage/backend
    cd packages/shared && npm test -- --coverage --coverageDirectory ../../coverage/shared

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    multiple-files: |
      Frontend, ./coverage/frontend/coverage-summary.json
      Backend, ./coverage/backend/coverage-summary.json
      Shared Utils, ./coverage/shared/coverage-summary.json
    multiple-junitxml-files: |
      Frontend Tests, ./coverage/frontend/junit.xml
      Backend Tests, ./coverage/backend/junit.xml
      Shared Tests, ./coverage/shared/junit.xml

Output: Combined table showing coverage and test results for all packages.

Matrix Strategy

Multiple Node.js versions with separate comments

strategy:
  matrix:
    node-version: [16, 18, 20]

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-node@v4
    with:
      node-version: ${{ matrix.node-version }}
  - run: npm ci
  - run: npm test -- --coverage
  - name: Jest Coverage Comment
    uses: MishaKav/jest-coverage-comment@main
    with:
      unique-id-for-comment: node-${{ matrix.node-version }}
      title: Coverage Report (Node.js ${{ matrix.node-version }})

Output: Separate coverage comments for each Node.js version, each updating independently.

Workflow Dispatch Support

Manual coverage reporting with issue number

name: Manual Coverage Report
on:
  workflow_dispatch:
    inputs:
      pr_number:
        description: 'Pull Request number'
        required: true
        type: string

jobs:
  coverage:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Install dependencies
        run: npm ci
      - name: Run tests with coverage
        run: npx jest --coverage --coverageReporters json-summary
      - name: Jest Coverage Comment
        uses: MishaKav/jest-coverage-comment@main
        with:
          issue-number: ${{ github.event.inputs.pr_number }}

Usage: Manually trigger this workflow and provide a PR number to get coverage comments on that specific pull request.

Output: Coverage comment will be posted to the specified pull request, even when not triggered by the PR itself.

Changed Files Only

Show coverage only for files changed in the PR

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    report-only-changed-files: true
    title: Coverage for Changed Files

Output:

• In PR: Shows coverage only for files modified in the PR
• No changes: Shows message "report-only-changed-files is enabled. No files were changed in this commit :)"

Note: Only works with pull_request and push events.

Auto-Update README Badge

Update coverage badge in README without commits

name: Update Coverage Badge
on:
  push:
    branches: [main]

jobs:
  coverage:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm test -- --coverage

      - name: Jest Coverage Comment
        id: coverage
        uses: MishaKav/jest-coverage-comment@main
        with:
          hide-comment: true

      - name: Dynamic Badges
        if: github.ref == 'refs/heads/main'
        uses: Schneegans/[email protected]
        with:
          auth: ${{ secrets.GIST_SECRET }}
          gistID: your-gist-id-here
          filename: coverage.json
          label: Coverage
          message: ${{ steps.coverage.outputs.coverage }}%
          color: ${{ steps.coverage.outputs.color }}

🔬 Advanced Features

📊 Using Output Variables

- name: Jest Coverage Comment
  id: coverage
  uses: MishaKav/jest-coverage-comment@main

- name: Dynamic Badges
  uses: Schneegans/[email protected]
  with:
    auth: ${{ secrets.GIST_SECRET }}
    gistID: your-gist-id
    filename: coverage.json
    label: Coverage
    message: ${{ steps.coverage.outputs.coverage }}%
    color: ${{ steps.coverage.outputs.color }}

- name: Fail if coverage too low
  if: ${{ steps.coverage.outputs.coverage < 80 }}
  run: |
    echo "Coverage is below 80%!"
    exit 1

⚡ Performance Optimization

For large coverage reports that might exceed GitHub's comment size limits:

- name: Jest Coverage Comment
  uses: MishaKav/jest-coverage-comment@main
  with:
    hide-summary: true # Show only badge and test results
    report-only-changed-files: true # Only show changed files
    remove-links-to-files: true # Remove clickable file links
    remove-links-to-lines: true # Remove clickable line number links

Link Removal Options:

• remove-links-to-files: true - Removes clickable links to files. Instead of [example.js](link), shows plain example.js
• remove-links-to-lines: true - Removes clickable links to line numbers. Instead of [14-18](link), shows plain 14-18

These options significantly reduce comment size while preserving all coverage information.

🎨 Badge Colors

Coverage badges automatically change color based on the percentage:

Coverage	Badge	Color
0-40%		Red
40-60%		Orange
60-80%		Yellow
80-90%		Green
90-100%		Bright Green

📸 Result Examples

View example outputs

Complete Comment Example

My Jest Coverage Comment

My Summary Title

Lines	Statements	Branches	Functions
	76.74% (33/43)	33.33% (2/6)	100% (0/0)

My JUnit Title

Tests	Skipped	Failures	Errors	Time
6	0 💤	0 ❌	0 🔥	1.032s ⏱️

My Coverage Title (78%)

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	76.74	100	33.33	78.57
src	75.67	100	40	75.67
controller.js	63.63	100	50	63.63	14–18
index.js	85.71	100	0	85.71	9
router.js	100	100	100	100
service.js	69.23	100	50	69.23	16–20
src/utils	83.33	100	0	100
config.js	100	100	100	100
utils.js	75	100	0	100

Text Mode Example

With text-instead-badge: true:

Lines	Statements	Branches	Functions
78.57% (33/42)	76.74% (33/43)	33.33% (2/6)	100% (0/0)

Coverage Summary Report

Coverage Console Report

JUnit Test Report

Multiple Files (Monorepo)

🔧 Troubleshooting

Common Issues and Solutions

Comment Not Appearing

Problem: The action runs successfully but no comment appears on the PR.

Solutions:

• Ensure proper permissions are set:

  permissions:
    contents: read
    pull-requests: write

• Check if hide-comment is set to false
• Verify the action is running on supported events (pull_request, push, workflow_dispatch, workflow_run)
• For workflow_dispatch or workflow_run events, ensure issue-number input is provided

Coverage Report Too Large

Problem: "Comment is too long (maximum is 65536 characters)"

Solutions:

• Use report-only-changed-files: true
• Set hide-summary: true to show only badge
• Use remove-links-to-files: true to remove clickable file links
• Use remove-links-to-lines: true to remove clickable line number links
• Use ["text-summary", { "skipFull": true }] in Jest coverage reporters to skip fully covered files

Coverage Shows 0%

Problem: Jest not collecting coverage for your files

Solutions:

// Check collectCoverageFrom in jest.config.js
collectCoverageFrom: ['src/**/*.{js,ts}', '!src/**/*.test.{js,ts}']

Files Not Found

Problem: "No such file or directory" errors

Solutions:

• Use absolute paths or paths relative to $GITHUB_WORKSPACE
• Check that coverage files are generated before the action runs
• Verify Jest configuration generates required files

Wrong File Links

Problem: Links in the coverage report point to wrong files or 404

Solutions:

• Use coverage-path-prefix if your test paths differ from repository structure
• Ensure the action runs on the correct commit SHA

Workflow Dispatch Events

Problem: Need to trigger coverage reporting on specific PRs manually

Solutions:

• Use issue-number input to specify the target PR:

  - name: Jest Coverage Comment
    uses: MishaKav/jest-coverage-comment@main
    with:
      issue-number: 123 # Replace with actual PR number

• For workflow_dispatch, add input parameter:

  on:
    workflow_dispatch:
      inputs:
        pr_number:
          description: 'Pull Request number'
          required: true

🤝 Contributing

We welcome all contributions! Please feel free to submit pull requests or open issues for bugs, feature requests, or improvements.

Development Setup

# Clone the repository
git clone https://github.com/MishaKav/jest-coverage-comment.git
cd jest-coverage-comment

# Install dependencies
npm install

# Run tests
npm test

# Build the action
npm run build

# Package for distribution
npm run package

👥 Contributors

📄 License

MIT © Misha Kav

---

🔗 Similar Actions

For Python projects using pytest: Check out pytest-coverage-comment - a similar action for Python test coverage with pytest.

---

If you find this action helpful, please consider giving it a ⭐ on GitHub!