Test coverage: 46% of lines, 2 of 29 classes fully covered, no end-to-end test

[loevgaard]

Current state

vendor/bin/phpunit --coverage-text with pcov on PHP 8.4:

Classes:  6.90% (2/29)
Methods: 30.00% (21/70)
Lines:   45.91% (129/281)

Only ConfigurationBasedPixelProvider and SetonoMetaConversionsApiExtension are fully covered. Most subscriber coverage comes from getSubscribedEvents() being called during kernel boot, not from their behaviour being exercised.

The untested code is exactly where the issues from the review live:

Area	Missing tests
Context\Fbc\*, Context\Fbp\*	cookie parsing (valid, invalid, missing), query override, cache behaviour, no-request behaviour, reset
StoreFbpSubscriber, StoreFbcSubscriber	cookie set and renewal after two hours, fbclid presence, consent gate, sub-requests, httpOnly=false
StoreTestEventCodeSubscriber, PopulateTestEventCodePropertySubscriber	store, read, clear, no session, no previous session
PopulateRequestPropertiesSubscriber	URL, IP and user agent populated; no request
PopulateFbpAndFbcPropertiesSubscriber, PopulatePixelsSubscriber	values copied onto the event
FilterBotsSubscriber, FilterEmptyUserAgentSubscriber, StopPropagationIfNoPixelsHasBeenAddedSubscriber	stop / do not stop
ConsentChecker	disabled → granted; enabled without checker → granted; enabled with checker → delegated with the configured category
SendEventHandler	delegates to ClientInterface; behaviour on ClientException
AddEventToTagBagSubscriber, AddLibraryToTagBagSubscriber	tags added with the expected priorities and fingerprints, init tag replacement, consent gate, no pixels
Configuration	defaults, client_side default depending on tag bag presence, pixels validation, filters.user_agent validation
SetonoMetaConversionsApiExtension::prepend()	its behaviour, or its removal
End to end	dispatch a ConversionsApiEventRaised through a booted kernel with a request on the stack and assert: (a) a stubbed ClientInterface receives the event with populated request properties, pixels and fbp; (b) with client side enabled the tag bag contains the pixel, init and track tags; (c) a bot user agent results in nothing being sent

Suggested approach

• Unit tests with plain Request, RequestStack, RequestEvent and ResponseEvent objects are cheap for every subscriber; no kernel needed.
• One KernelTestCase end-to-end test using Nyholm\BundleTest\TestKernel, a ClientInterface stub registered through a test compiler pass, and Messenger in sync mode. This single test would have caught prepend() replaces the application's default Messenger bus #12.
• Make the CI coverage job fail below a threshold (Codecov status checks or a simple clover check) so coverage cannot regress silently.