In normal Flarum, extensions are only enabled during requests. Here, however, we enable some during boot. This resolves the FilesystemManager early, which resolves the Url Generator early. To fix this, we directly provide a filesystem disk for assets instead of getting it from the filesystem manager.
This ensures a clean state for the extension currently being tested. The alternative requires the user to create and keep track of multiple test databases, or manually delete/re-recreate the database every time they switch between extensions being tested. Now, a simple `composer test:setup` will always reset the test environment to the original state.
This allows adding settings before the app is booted. In the past we've used hacky workarounds like manually resetting a binding to override singletons to use custom setting values. It makes sense to support this through `TestCase`.
It's not causing any issue because the correct variable name is always used to set and read the value, and PHP is fine setting new attributes on a class dynamically. It's just the explicit variables declared don't match with those actually used later.
Core's ExtensionManager only looks for extensions in the vendor directory, which makes sense for a Flarum instance, but is problematic if used in the context of a test suite for an extension. This PR:
- Adds a class extending ExtensionManager to include the current package
- Adds an extender that replaces ExtensionManager with this new class in container bindings
Effectively, this package can now be used to test extensions.
