- Make WebServerFixture properties nullable to match async initialization
- Add null-coalescing assertions where properties are guaranteed non-null
- Fix GetDiscoveryDocumentAsync delegate signature in Remoting to allow nullable parameters
- Build now succeeds with 0 errors, 7/9 tests passing
- Add in-memory database support for test isolation in WebServerFixture
- Implement TestMailSender fake SMTP provider for email test support
- Add thread synchronization to billing service registration to prevent race conditions
- Make RegisterBilling<T> idempotent to safely handle reconfiguration
- Configure test environment via in-memory settings (UseTestEmailSender, UseInMemoryDatabase)
- Add regression tests for billing module idempotency and duplicate registration detection
- Fix tests: EMaillingTests.SendEMailSynchrone, BillingServiceTests (2 tests), HaveConfigurationRoot (3 tests)
All core test infrastructure tests now passing.
