Jacoco Report GitHub Action

Automates the publication of JaCoCo coverage reports directly as comments in pull requests.

• Requirements
• Motivation
• Quick Start
• Usage
  • Action Inputs
  • Outputs
  • Examples
• Troubleshooting
• Migrating from v2
• Developer
• License
• Donate

Requirements

• GitHub Token: A GitHub token with permission to fetch repository data such as Issues and Pull Requests.
• Python 3.14+: Ensure you have Python 3.14 installed on your system.

---

Motivation

Reviewing coverage numbers by hunting through CI logs is tedious. This action posts a structured coverage report as a PR comment — directly where the review happens — so the whole team can see which files changed, what their coverage is, and whether thresholds are met, without leaving GitHub.

Key capabilities:

• Global thresholds — enforce overall and average-changed minimums in one input.
• Report groups — organise multi-module projects into named groups with per-group thresholds.
• Baseline comparison — show Δ coverage against a stored baseline (e.g. the master branch reports).
• Flexible comment levels — from a single-line summary to full per-file detail, or no comment at all.
• Skip-unchanged filter — remove reports with no changed files from the comment (and optionally from evaluation).

---

Usage

name: Publish JaCoCo Report in PR comments

on:
  pull_request:
    types: [opened, synchronize, reopened, edited]
    branches: [ master ]

jobs:
  generate-report:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      issues: write
      pull-requests: read
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - uses: actions/setup-python@v5
        with:
          python-version: '3.14'

      - name: Publish JaCoCo Report in PR comments
        uses: MoranaApps/jacoco-report@v3
        with:
          token: '${{ secrets.GITHUB_TOKEN }}'
          paths: |
            src/reports/jacoco/jacoco.xml
            **/jacoco.xml
            **/reports/**/*.xml
            ${{ github.workspace }}/**/jacoco.xml
          global-thresholds: '80*70*60'       # overall * changed-avg * per-changed-file

---

Action Inputs

Name	Description	Required	Default
token	GitHub token for authentication with the repository.	Yes
paths	Newline-separated paths to JaCoCo XML files. Supports wildcard glob patterns. Required when report-groups is not set.	No	''
exclude-paths	Newline-separated paths to exclude from coverage analysis. Supports glob patterns.	No	''
global-thresholds	Global thresholds in overall*changed-files-average format.	No	0.0*0.0
report-thresholds-default	Default thresholds for reports/groups when a group omits a threshold field. Format: overall*changed-files-average*per-changed-file (e.g. 75*60*0). Field-level fallback chain: per-group → this default → 0.0.	No	0.0*0.0*0.0
title	Title for the coverage report comment added to the Pull Request.	No	JaCoCo Coverage Report
pr-number	Number of the pull request. If not provided, the action will attempt to determine the PR number from the GitHub context.	No	''
metric	Coverage metric to use (instruction, line, branch, complexity, method, class).	No	instruction
comment-level	Comment output level: none, minimal, full, changed, failed, or failed-or-changed. See docs/inputs/comment-level.md.	No	full
report-groups	Named report groups as a YAML list. Each entry: name (required), paths (required list of globs), thresholds (optional O*A*P), baseline-paths (optional list). See docs/inputs/report-groups.md.	No	''
skip-unchanged	If true, reports with no changed files are filtered out from comment rows. With default evaluate-unchanged=true, filtered reports can still affect threshold results.	No	false
evaluate-unchanged	Applies only when skip-unchanged=true. If true, filtered reports can still fail overall thresholds. If false, they are excluded from threshold evaluation as well.	No	true
baseline-paths	Paths to baseline coverage reports for comparison. Supports wildcard glob patterns.	No	''
update-comment	If true, updates an existing comment instead of creating a new one.	No	true
pass-symbol	Symbol for passing checks in PR comments (e.g., ✅, Passed).	No	✅
fail-symbol	Symbol for failing checks in PR comments (e.g., ❌, Failed).	No	❌
fail-on-threshold	List value (comma- or newline-separated) of thresholds that must pass: overall, changed-files-average, per-changed-file, fail-unchanged. Leave empty to disable.	No	overall,changed-files-average,per-changed-file
debug	Enables detailed logging. Automatically activated when RUNNER_DEBUG=1 (GitHub runner debug mode).	No	false

---

Outputs

The following outputs are set by the JaCoCo GitHub Action:

• coverage-overall: The overall code coverage percentage. Example: 85.38
• coverage-changed-files: The code coverage percentage for the changed files. Example: 79.21
• coverage-overall-passed: A boolean indicating if overall code coverage meets the configured threshold. Example: True
• coverage-changed-files-passed: A boolean indicating if changed-files average coverage meets the configured threshold. Example: True
• reports-coverage: A JSON string containing the evaluated coverage per report. Example:

  {
      "path/to/jacoco.xml": {
          "name": "My Report",
          "group_name": "Unknown",
          "overall_passed": true,
          "overall_coverage_reached": 85.38,
          "overall_coverage_threshold": 80.0,
          "overall_coverage": { "missed": 142, "covered": 934 },
          "avg_changed_files_passed": true,
          "avg_changed_files_coverage_reached": 79.21,
          "avg_changed_files_coverage": { "missed": 21, "covered": 80 },
          "changed_files_passed": { "src/main/java/Foo.java": true },
          "changed_files_threshold": 70.0,
          "changed_files_coverage_reached": { "src/main/java/Foo.java": 82.5 },
          "per_changed_file_threshold": 70.0
      }
  }

• groups-coverage: A JSON string containing the evaluated coverage per report group (populated when report-groups is defined). Example:

  {
      "backend": {
          "name": "backend",
          "group_name": "backend",
          "overall_passed": true,
          "overall_coverage_reached": 85.38,
          "overall_coverage_threshold": 80.0,
          "overall_coverage": { "missed": 142, "covered": 934 },
          "avg_changed_files_passed": true,
          "avg_changed_files_coverage_reached": 79.21,
          "avg_changed_files_coverage": { "missed": 21, "covered": 80 },
          "changed_files_passed": { "src/main/java/Foo.java": true },
          "changed_files_threshold": 70.0,
          "changed_files_coverage_reached": { "src/main/java/Foo.java": 82.5 },
          "per_changed_file_threshold": 70.0
      }
  }

---

Examples

• Paths and Exclude Paths
• Global Coverage Thresholds, Per-file Thresholds, and Fail-on-Threshold
• Report Groups
• Comment Level
• Skip Unchanged and Evaluate Unchanged
• Baseline Paths
• Symbols and Metric Type
• PR Number, Title, and Update Comment
• Debug Mode

---

Troubleshooting

The action cannot find any JaCoCo XML files

• Check that your build step runs before this action and actually produces the XML files.
• Use debug: 'true' to log matched JaCoCo XML files discovered by scanning.
• Verify the paths pattern resolves to real files. Both repository-relative patterns and absolute ${{ github.workspace }} paths are supported.
• If the path contains a leading * in a report-groups YAML block, wrap it in quotes: - '**/jacoco.xml'.

No PR comment is posted

• Confirm comment-level is not set to none.
• Confirm the job token permissions include issues: write (comment create/update/delete) and pull-requests: read (PR files lookup).
• If skip-unchanged: true and all reports have no changed files:
  • with evaluate-unchanged: false, the action exits cleanly with no comment by design;
  • with evaluate-unchanged: true (default), unchanged reports are still evaluated for threshold failures.

The action fails with a threshold error but the comment shows ✅

• Check whether fail-on-threshold lists dimensions that differ from the thresholds you set in global-thresholds and report-thresholds-default. By default, overall, changed-files-average, and per-changed-file checks are enabled; the per-changed-file check uses report/group thresholds.
• When report-groups is used, group thresholds are evaluated separately from global-thresholds.

fail-on-threshold selection looks incorrect

• Ensure fail-on-threshold is configured as a list value (comma- or newline-separated).

• Example:

  fail-on-threshold: 'overall,changed-files-average,per-changed-file'

Migrating from v2

See docs/v2-v3-migration-guide.md for a full before/after guide covering every breaking change.

---

Developer

Follow the DEVELOPER.md guide to set up the development environment.

License

Apache License, Version 2.0

Donate

If you find this project useful or interesting, consider supporting it!

Your donation helps me keep building, maintaining and improving this tool — every bit of support matters and is deeply appreciated.

• Buy me a coffee on Ko-fi

Thanks for keeping this project alive.