github-action/docs/wiki/CodeMetrics.md

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Showing code metrics and coverage badges

How a software engineer calls the shared code-metrics workflow and shows its three badges (code files, lines of code and coverage) in a README. The workflow counts the code of the repository, reads a coverage report that the caller supplies and commits three SVG files to a badges branch. It runs no test and needs no secret. Its contract is ADR-0010 in this repository.

Calling the workflow

The workflow cannot see the files of your test job, so the tests run in a job of your own, upload the Cobertura XML report as an artifact, and the metrics job runs after it:

name: Code metrics

on:
  push:
    branches: [ main ]

jobs:
  tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4.2.2
      - run: python3 -m pip install pytest pytest-cov && python3 -m pytest --cov --cov-report=xml
      - uses: actions/upload-artifact@v4.6.2
        with:
          name: coverage
          path: coverage.xml

  metrics:
    needs: tests
    permissions:
      contents: write
    uses: TirSystem/github-action/.gitea/workflows/code-metrics.yml@v2
    with:
      coverage-artifact: coverage
      coverage-report: coverage.xml

Input	Default	Meaning
working-directory	.	Directory, relative to the repository root, whose code is counted
exclude	empty	Comma list of patterns of files and directories that are not counted, in addition to the defaults; a pattern without / matches a name anywhere, a pattern with / matches the path below working-directory
coverage-report	empty	Cobertura XML report: the file inside the artifact when coverage-artifact is set, otherwise a path in the repository; empty writes no coverage badge
coverage-artifact	empty	Name of an artifact, uploaded by an earlier job of the same run, that holds the report
coverage-warn	60	Coverage in percent below which the badge is red
coverage-good	80	Coverage in percent from which the badge is green; in between it is yellow
badges-branch	badges	Branch that holds the badge files; it is created when it does not exist
tools-ref	v2	Tag or branch of TirSystem/github-action from which the scripts in tools/ are fetched

Reference the workflow at the major tag (@v2) or at an exact tag, never at main. A call at an exact tag is pinned completely only when tools-ref names the same tag. See the upgrade guide. Start the workflow on pushes to your default branch only: the badge commit carries [skip ci] and is made with the token of the run, which does not start another run, but a trigger on every branch would write one commit per branch.

What is counted

• A code file is a text file with the extension of a supported language: Python, shell, PowerShell, C, C++, C#, Java, JavaScript, TypeScript, Go, Rust and SQL. Markdown, YAML, JSON, XML, HTML and CSS are not code files.
• Every line is exactly one of blank (only white space), comment (only comment text) or code (everything else, including a line with code and a trailing comment). The badge shows the lines of code only.
• A comment marker inside a string is not a comment, and a Python docstring is a string, so it counts as code.
• Directories that start with a dot and node_modules, vendor, third_party, dist, build, out, bin, obj, target, venv, __pycache__ and shared-scripts are not counted. Generated code is excluded with exclude.
• Raw and verbatim strings that differ from an ordinary string (Rust r#"..."#, C# @"...", C++ raw strings) can be counted wrongly. The counts will differ a little from other tools; the rules are the same on every run.

The coverage badge

The report is a Cobertura XML file, which coverage.py (coverage xml), gcovr (--cobertura) and coverlet (cobertura format) write. The badge shows lines-covered over lines-valid, rounded to a whole percent, and its colour follows the two thresholds. A report that does not exist, is not well-formed Cobertura XML or has no valid lines fails the run with the file named; the coverage badge is never written as 0% for a bad report. Without coverage-report the run passes with a notice and no coverage badge.

Showing the badges

Add the images to the README with the raw URLs of the branch:

![code files](https://git.tirsystem.com/OWNER/REPO/raw/branch/badges/code-files.svg)
![lines of code](https://git.tirsystem.com/OWNER/REPO/raw/branch/badges/code-lines.svg)
![coverage](https://git.tirsystem.com/OWNER/REPO/raw/branch/badges/coverage.svg)

On the GitHub mirror use https://raw.githubusercontent.com/OWNER/REPO/badges/code-files.svg; the push mirror copies the branch. The badges branch also holds code-metrics.json with the numbers per language. The instance caches a raw file for up to six hours, so a changed badge can show the old number for a while there; the mirror caches for five minutes. A private repository does not show the badges to a reader who is not signed in.

When the workflow fails

Message	Cause	Fix
[configuration] working-directory must be a relative path inside the repository.	An absolute path or ..	Use a path inside the repository
[configuration] coverage-report '<x>' does not exist.	The report was not produced, or the artifact name or path is wrong	Check the test job and the artifact name; the path is inside the artifact
[configuration] coverage-report '<x>' is not well-formed XML or is not a Cobertura report	The file is another format	Write Cobertura XML (coverage xml, gcovr --cobertura)
[configuration] coverage-report '<x>' has no valid lines.	The tests ran no measured code	Check the coverage configuration
[configuration] coverage-artifact '<x>' needs coverage-report	The artifact is named but not the file in it	Set coverage-report
[configuration] coverage-warn ... is above coverage-good or is not a number from 0 to 100	A threshold is invalid	Correct the input
[configuration] badges-branch '<x>' must not be a default branch or holds files that are not badge files	The branch name is main, master or a branch with other content	Use a branch that holds only the badges
the push to '<x>' failed twice	Another run wrote the branch at the same time, or the token cannot write	Re-run; check that the job has contents: write
The download step fails	The artifact does not exist in this run, or the job does not run after the test job	Add needs: and check the artifact name