Test coverage

composer require quillstack/test-coverage

PackagistSourcePHP ^8.1

A library to create test coverage reports in PHP.

What quillstack/unit-tests uses to say how much of a package its tests actually run, and to write the report SonarCloud reads. It needs no extension: coverage comes from phpdbg, which ships with PHP.

Why this exists

Coverage in PHP usually means Xdebug or PCOV — an extension to install, in development and in CI, before a number appears. This uses phpdbg, which ships with PHP itself, so measuring what the tests reached needs nothing that is not already there.

It also counts a file no test loaded at all, which is the number that matters most and the one an incomplete report quietly leaves out. A class nobody instantiated is not absent from the report; it is zero per cent of it.

Requirements

• PHP 8.1 or newer
• phpdbg, to measure anything — without it the tests still run, just without a number

Installation

composer require --dev quillstack/test-coverage

Usage

use Quillstack\TestCoverage\CoverageOutput\CoverageXml;
use Quillstack\TestCoverage\Drivers\PHPDbg;
use Quillstack\TestCoverage\Drivers\NoCoverage;
use Quillstack\TestCoverage\TestCoverage;

$coverage = new TestCoverage(
    PHPDbg::isAvailable() ? new PHPDbg() : new NoCoverage(),
    new CoverageXml()
);

$coverage->start();
// … run the tests …
$coverage->end();

$xml = $coverage->process(__DIR__ . '/src', __DIR__);
$summary = $coverage->getSummary();
// ['covered' => 54, 'total' => 61, 'percent' => 88.5, 'files' => 4]

Run it under phpdbg, which is a separate binary shipped with PHP:

phpdbg -qrr vendor/bin/unit-tests

A file nothing loaded still counts

phpdbg knows nothing about a file which was never compiled, so a class no test ever touched would drop out of the report altogether — and the percentage would come out better than the truth. Every file under the directory is compiled first, which puts its lines back into the total as uncovered.

It is not a small difference: it took one package in this stack from a reported 94.6% to an honest 80.3%.

Technical documentation

Class	What it is
TestCoverage	the way in: starts, stops, processes, and summarises
Drivers\PHPDbg	measures with phpdbg
Drivers\NoCoverage	measures nothing, so tests still run where phpdbg is not there
CoverageOutput\CoverageXml	writes the report Sonar and friends read

TestCoverage implements TestCoverageInterface:

Method	Does
isAvailable(): bool	whether anything can be measured at all
start(): void / end(): void	begin and end collecting
process(string $dir, string $rootDir = ''): string	the report, as a string
getSummary(): array	covered, total, percent, files of the last run

$rootDir is taken off the front of every path, because the report is read somewhere other than the machine which wrote it and an absolute path from a CI runner matches nothing.

A driver implements TestCoverageDriverInterface (isAvailable(), start(), end(), process()), and an output implements TestCoverageOutputInterface (generate()) — so another way of measuring, or another format, is one class either way.

Benchmark

There is no timing table here, and the reason is worth a sentence rather than a number.

Coverage is collected by the runtime — phpdbg here, Xdebug or PCOV for phpunit/php-code-coverage — and what that costs is a property of the extension, not of the library reading its output. Timing the two libraries would be timing three different collectors and calling the difference ours.

What can be compared honestly is what each brings with it:

	Version	Installed	Packages
quillstack/test-coverage	v0.6.3	120 kB	1
phpunit/php-code-coverage	11.0.12	1.4 MB	11

And what those eleven packages buy is real: branch and path coverage, not just lines; HTML, Clover, Cobertura, Crap4J and PHP report formats; a static analysis pass that knows which lines are executable before anything runs; and support for Xdebug and PCOV as well as phpdbg. This produces line coverage and a Clover file.

If you already have Xdebug and want branch coverage or an HTML report, that is the one to use.

Tests

composer test
composer test:coverage
composer stan

The driver is exercised in a process of its own, because phpdbg collects into one log at a time and starting a second inside this suite would take its own measurement away from it. That work therefore does not show up in this package's own percentage: the seven lines it reports as uncovered are the ones only a live log reaches, and they are tested out there.

The rest of Quillstack

This is one component of Quillstack, a PHP framework which is as simple to use as it is strict about what it does.

• quillstack/unit-tests — which runs the tests being measured
• quillstack/benchmark — how long things take, rather than what ran
• quillstack/standards — which checks a package is as it should be

License

MIT. See LICENSE.