saqel/backend/.agents/skills/testing-best-practices/rules/performance.md

Test Suite Performance

These settings apply to the project and CI, not to individual tests. Read rules/isolation.md for choices within a test.

Fetch https://docs.phpunit.de/en/13.3/ for PHPUnit options that make test runs faster. Verify each flag in the documentation before adding it to CI.

Measure before changing a setting. Find the slow test first, and apply a project-wide setting only after identifying the costly work.

The Environment

• Set BCRYPT_ROUNDS=4 in .env.testing or in phpunit.xml. The default value is 12, and the hash then takes most of the time of each test that signs a user in.
• Disable XDebug. Disable pcov also, unless the run needs the coverage.
• Disable packages that perform work on every request in the test environment. Examples are Pulse, Telescope, and Nightwatch.
• Use the WithCachedConfig and WithCachedRoutes traits, so the run does not parse the configuration and the routes for every test.
• Call withoutVite(), or withoutMix(), so the framework does not resolve a built asset.

The Global Fakes

Put these three calls in the setUp() of the base TestCase of the project:

• Http::preventStrayRequests(), because one request that reaches the network can slow the suite. This catches requests made through Laravel's HTTP client. Check direct Guzzle and cURL usage separately.
• Sleep::fake(syncWithCarbon: true), so a retry and a backoff do not sleep.
• Exceptions::fake(), so the suite does not report an exception to an external service.

How to Run the Suite in Parallel

Run php artisan test --parallel, which uses ParaTest, to spread tests across the machine's CPU cores. Add --processes=N if the default count is unsuitable for the machine or CI.

A parallel run gives each process a separate database. Tests must meet these conditions; a test that fails only in parallel breaks one of them:

• The test creates each record that it reads. It does not read a record that another test creates.
• The test does not depend on the order of the run.
• The test does not share a file, a cache key, or a queue with another test. Give each process a separate name for such a resource.

How to Find a Slow Test

Run php artisan test --profile to list the slowest tests. Start with the ten slowest tests, because the same cause often applies to the complete suite.

If the cause of a slow test is unclear, add an event listener or temporary log entry to identify its work.

Common Errors

• The run loads XDebug for a test that does not need it.
• BCRYPT_ROUNDS keeps the default value, because the project has no .env.testing.
• The code under test calls the real sleep(), and Sleep::fake() then does not help.