PHPUnit runner bundle can omit DefaultTestResultCache autoload mapping

[chubes4]

Problem

A managed wordpress.phpunit workload can mount PHPUnit's TextUI/TestRunner.php while its Composer autoloader cannot resolve PHPUnit\\Runner\\DefaultTestResultCache.

Observed with WP Codebox 0.12.14 through Homeboy's WordPress test extension:

wordpress.phpunit could not run: Error: Class \"PHPUnit\\Runner\\DefaultTestResultCache\" not found at /tmp/wp-codebox-inputs/.../phpunit/phpunit/src/TextUI/TestRunner.php:195

The plugin under test has a tracked Composer lockfile but does not itself require PHPUnit. WP Codebox supplies the PHPUnit/wp-phpunit input bundle. The runtime reaches run_workloads, installs WordPress, mounts the plugin, and then fails before discovering or executing any tests.

Reproduction

Run a managed WordPress PHPUnit recipe against a plugin that has phpunit.xml tests but does not declare phpunit/phpunit in its own Composer requirements. Pass any filter. The generated command uses the WP Codebox vendor input as autoload-file; TestRunner loads, but DefaultTestResultCache does not.

Expected

The PHPUnit distribution and autoloader supplied by WP Codebox are internally complete and version-aligned. A component should not need to add a redundant PHPUnit dependency merely to repair the runtime-owned test runner.

Evidence

• failure phase: run_workloads
• WP Codebox package: 0.12.14
• runtime artifact command: wordpress.phpunit
• no tests execute (total: 0)
• the prior archive-cache lock was independently cleared; this failure occurs after successful runtime startup

[chubes4]

Resolved on current main (46487a41) by the already-merged owner-layer fix in #1950 (50d2d220, merge 40b6a33c). No additional PR is needed.

Root cause

This was a partial staged-mount materialization failure, not an incomplete or version-misaligned PHPUnit package. Playground's direct writer could return successfully while silently omitting a generated Composer companion file. In the observed shape, enough of the PHPUnit tree/autoload metadata survived to load PHPUnit\TextUI\TestRunner, but the optimized static loader was incomplete because vendor/composer/autoload_static.php was missing or stale, so PHPUnit\Runner\DefaultTestResultCache was not autoloadable.

#1950 fixed the generic owner layer in packages/runtime-playground/src/mount-materialization.ts: every successful direct staged-file write is now hash-verified in the persistent PHP runtime; missing or mismatched files are rewritten there and verified again. tests/mount-materialization.test.ts specifically models an accepted autoload_real.php write plus a silently dropped autoload_static.php and asserts repair.

Current-main reproduction evidence

The exact consumer condition no longer reproduces. tests/playground-phpunit-readonly-cache.integration.test.ts creates a plugin with PHPUnit tests and phpunit.xml.dist but no plugin composer.json and no project PHPUnit dependency. It separately installs the runtime-owned fixture from tests/fixtures/phpunit-playground-harness/composer.json (phpunit/phpunit 9.6.34 with optimized/classmap-authoritative autoloading), mounts only that vendor tree at /wp-codebox-vendor, runs a real managed wordpress.phpunit recipe, and requires DISCOVERY ... found=1 plus entry into run_tests.

Executed from clean branch fix/1985-phpunit-autoload at 46487a41:

• npm ci - passed; its prepare hook ran npm run build, which passed
• npx tsx tests/mount-materialization.test.ts - passed: mount materialization ok
• npx tsx tests/phpunit-project-autoload.test.ts - passed: phpunit project autoload ok
• npm run test:playground-phpunit-readonly-cache-integration - passed: playground phpunit readonly cache integration ok
• git diff --check - passed
• Worktree remained clean; no files changed

Compatibility impact

The repair is generic and version-agnostic: it establishes byte-for-byte completeness for all staged mount files rather than adding PHPUnit- or Composer-specific branches. Consumers no longer need to declare a redundant phpunit/phpunit dependency to compensate for an incomplete runtime mount. Existing complete mounts are unchanged aside from verification.