Parallel tests fail first then pass with Livewire components

When I run php artisan optimize:clear if I run tests in parallel using php artisan test -p I get the following error in Livewire component views:

..............................................................  62 / 387 ( 16%)
..............................................F............... 124 / 387 ( 32%)
.............................................................. 186 / 387 ( 48%)
...............F.............................................. 248 / 387 ( 64%)
..................E........................................... 310 / 387 ( 80%)
.............................................................. 372 / 387 ( 96%)
...............                                                387 / 387 (100%)

....

Undefined array key 1 (View: C:\...\standard-fields.blade.php) (View: C:\...\standard-fields.blade.php)
ErrorException: Undefined array key 1 in C:\...\vendor\livewire\livewire\src\LivewireManager.php:425
...

Undefined array key 1 (View: C:\...\containers.blade.php) (View: C:\...\containers.blade.php) (View: C:\...\containers.blade.php)

Sometimes, there are 2 failures, sometimes 3. It keeps changing.

If I repeat the same tests again by re running the command php artisan test -p all tests pass. Subsequently all test runs pass. It is just the first one after the clear which fails.

This also happens if I run php artisan view:clear and then run the tests in parallel with php artisan test -p - it causes the errors to appear. So it feels like cached views are needed for parallel testing for some reason and there are only a few Livewire components where this error repeatedly pops up.

This only happens in parallel testing i.e., if I run php artisan optimize:clear or php artisan view:clear and then run php artisan test without the -p flag it works without any errors.

I am not sure where to even start debugging this so any advice is appreciated.

Livewire version: v2.12.6 Paratest version: v7.3.1

LaryAI

2 years ago

Level 58

It seems like the issue you're encountering is related to race conditions that can occur when running tests in parallel. When you clear the view cache, the first request that hits a Livewire component will try to compile the view and cache it. If multiple parallel processes try to compile and cache the same view at the same time, it can lead to the errors you're seeing.

Here are a few steps you can take to try and resolve this issue:

Pre-compile your views before running tests in parallel. This can be done by running a single test that hits all Livewire components to ensure that all views are compiled and cached before running the full test suite in parallel.

php artisan view:cache

Ensure that your Livewire components are not doing anything non-thread-safe in their rendering logic that could cause race conditions when cached views are being generated.
If the issue persists, you might want to look into isolating the tests that use Livewire components and run them sequentially instead of in parallel. You can use PHPUnit groups to separate these tests.
As a last resort, if you're unable to resolve the race condition, you might consider disabling view caching for your test environment. This can be done by setting the VIEW_CACHE environment variable to false in your .env.testing file.

VIEW_CACHE=false

Finally, ensure that your Livewire version is up to date, as there may have been bug fixes related to parallel testing in newer versions.

composer update livewire/livewire

Remember that parallel testing can introduce complexities due to concurrent access to shared resources. It's important to ensure that your application is designed to handle these conditions when running tests in parallel.

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