Why?

coverdata easily converts Erlang cover data files into a JSON object for simple integration with a Shields IO Dynamic JSON badge to show a code coverage level updated with each build:

What?

This repository creates an escript that reads coverage data from .coverdata files, outputting a JSON object of the percentage coverage per module and the total coverage percentage.

Without an --input argument cover2json will import all .coverdata files under the current directory.

cover2json --output _site/cover/coverage.json

Each module has a coverage rate, with total being combined rate:

{
  "total": 67,
  "scran_combinator": 96,
  "scran_debug": 0,
  "scran_number_be": 5,
  "scran_number": 23,
  "scran_multi": 97,
  "scran_bytes": 83,
  "scran_branch": 100,
  "scran_sequence": 95,
  "scran_result": 33,
  "scran_number_le": 0,
  "scran_bits": 100,
  "scran_character_complete": 98
}

Options:

• --input is a single filename of .coverdata to load (optional)
• --output is an output filename for the JSON object (required)
• --level LEVEL is the analyse level for cover to use. Only module is supported at present, and is the default (optional)
• --format FORMAT is the output format to use, currently only json is supported (default, optional).

coverdata can be used as part of a GitHub Action copying the JSON object into a GitHub Pages environment. A shields.io dynamic JSON badge can then use the coverage.json as input.

In this GitHub Action fragment:

  site:
    needs: build
    strategy:
      matrix:
        otp:
          - 26
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: erlef/setup-beam@v1
        with:
          otp-version: ${{matrix.otp}}
      - run: make tests edoc
      - uses: shortishly/coverdata@main
        with:
          input: _site/cover
          output: _site/cover/coverage.json
          otp-version: ${{matrix.otp}}
      - uses: actions/upload-pages-artifact@v1
        with:
          path: _site

The site job runs the tests with coverage enabled, generating edoc which are output into directories under _site, which are then uploaded to GitHub Pages via the actions/upload-pages-artifact@v1. Each successful build will update the _site/cover/coverage.json.

The README.md references the current coverage level via (using scran as a live example):

<a href="https://shortishly.github.io/scran/cover/">
  <img alt="Test Coverage" src="https://img.shields.io/badge/dynamic/json?url=https%3A%2F%2Fshortishly.github.io%2Fscran%2Fcover%2Fcoverage.json&query=%24.total&suffix=%25&style=flat-square&label=Test%20Coverage&color=green">
</a>

The encoded URL used points to the generated coverage.json on the GitHub Pages environment used by the project:

https://shortishly.github.io/scran/cover/coverage.json

The query into the JSON object is $.total to select the total coverage of the project within the badge.

Build

coverdata uses erlang.mk.

To fetch dependencies and compile:

make app

To run the unit tests:

make tests