PHP Coverage Filter

• Run only the tests that cover lines that have been changed.
• View the report for only files that have been changed.

Install

composer require --dev brianhenryie/php-diff-test

Requires XDEBUG_MODE=coverage.

Run

difffilter

Prints a filter to use with PHPUnit or Codeception, so you only run tests relevant to changes in the branch you're working on.

• Run: phpunit --filter="$(difffilter)" or codecept run suitename "$(difffilter)".
• Try just difffilter to see the filter that will be applied, which is effectively difffilter --input-files <glob *.cov> --diff-from main --diff-to HEAD^.
• Try difffilter --diff-from HEAD~3 to print a shallower diff.

diffcoverage

Outputs a new .cov file containing only the files whose lines have been changed in the diff. Intended to then print a HTML coverage report

• Run: diffcoverage --input-files "php-coverage1.cov,php-coverage2.cov" --diff-from main --diff-to HEAD^ --output-file diff-coverage/diff-from-to.cov
• Then to generate the new HTML report: phpcov merge --html ./diff-coverage/report ./diff-coverage. NB phpcov will merge all .cov files in the directory and subdirectories so you should set diffcoverage's new .cov --output-file to be in its own directory.

How it works

Runs git diff, parses which lines have been changed, parses *.cov codecoverage files to match which tests cover those lines.

The script looks in the current working directory, its tests subfolder, and each of the tests immediate subfolders for *.cov.

It also checks tests for Codeception *.suite.y*ml files, and assumes a file named unit.cov corresponds with unit.suite.yml to determine should the output be formatted for codecept run... syntax rather than PHPUnit --filter="..." syntax.

Obviously, it's assumed you're working inside a Git repo and have previously generated code coverage (in PHP .cov format).

⚠️ This has been tested to just over 500 test cases. It will inevitably have its limits, when you should probably use groups to first generate the coverage to be filtered.

TODO

• I think the diff doesn't track unstaged/uncommitted files which could have code coverage
• Also run tests changed in the diff / run all tests changed since the code coverage was generated (i.e. Tests written after the code coverage report are not included in the filter)
• Figure how best merge/increment coverage reports – i.e. once diffcoverage has been run on the full coverage report, add to it when new tests are written
• Allow specifying a hash to diff with – i.e. make pull requests run faster
• sebastianbergmann/php-code-coverage#571 – code coverage annotations make this tool less thorough
• Tidy up the code – I'm not sure is the diff report's lines the current lines or the before lines... use both for best effect
• Tests!