Feed the output of `phpunit --list-tests-xml <file.xml>` and slice it up into smaller chunks

phpunit_xml_slicer.php

#!/usr/bin/env php
<?php declare(strict_types = 1);

// Source: https://gist.github.com/mfn/256636242cbe8a51252ce28181a6b074

$command = array_shift($argv);

if (2 !== count($argv)) {
    echo "Please provide a XML file and a slice like `$command tests.xml 2/4`\n";

    exit(1);
}

if (!preg_match('/^([0-9]+)\/([0-9]+)$/', $argv[1], $parts)) {
    echo "Please provide the slice in form like  `$command tests.xml 2/4`\n";

    exit(1);
}

$tests = [];

$inputXml = simplexml_load_file($argv[0]);

foreach ($inputXml->testCaseClass as $class) {
    foreach ($class->children() as $method) {
        $tests[] = [$class, $method];
    }
}

foreach ($inputXml->phptFile as $phptFile) {
    $tests[] = $phptFile;
}

// Source: \Wizaplace\PHPUnit\Slicer\TestSuiteSlicer::slice
$slices = $parts[2];
$current = $parts[1] - 1; // 0 indexed. Slice 1 is in reality slice 0
$total = count($tests);
$testsPerSlice = (int) ceil($total / $slices);
$offset = $testsPerSlice * $current;

$slicedTests = array_slice($tests, $offset, $testsPerSlice);

$outputXml = new XMLWriter();
$outputXml->openMemory();
$outputXml->setIndent(true);
$outputXml->startDocument('1.0', 'utf-8');

$outputXml->startElement('tests');

foreach ($slicedTests as $slicedTest) {
    if (is_array($slicedTest)) {
        [$class, $method] = $slicedTest;
        $outputXml->startElement('testCaseClass');
        $outputXml->writeAttribute('name', $class['name']->__toString());

        $outputXml->startElement('testCaseMethod');
        $outputXml->writeAttribute('name', $method['name']->__toString());

        if ($method['groups']) {
            $outputXml->writeAttribute('groups', $method['groups']->__toString());
        }

        if ($method['dataSet']) {
            $outputXml->writeAttribute('dataSet', $method['dataSet']->__toString());
        }

        $outputXml->endElement();

        $outputXml->endElement();
    } else {
        $outputXml->startElement('phptFile');
        $outputXml->writeAttribute('path', $slicedTest['path']->__toString());
        $outputXml->endElement();
    }
}

$outputXml->endElement();
$outputXml->endDocument();
echo $outputXml->outputMemory();