Verify store registration consistency across tracing and factory configurations #608

Problem

The store-registration code in Stores.cs has approximately 12% line coverage in the October 5, 2026 .NET 10 coverage run. It contains separate paths for tracing, implementation-type registrations, and factory registrations. You can view a test coverage report I generated here: index.html

A host can build successfully while its reader and writer resolve to different backing stores or its tracing wrappers resolve incorrectly. Registration tests should therefore verify working reads and writes, not just successful service resolution.

Source: Stores.cs.

Proposed tests

• Build a minimal host using AddEventStore<T> and verify that an event written through IEventWriter can be read through IEventReader and accessed through IEventStore.
• Exercise both implementation-type and factory registration overloads with tracing enabled and disabled.
• Verify the corresponding read/write behavior for AddEventReaderWriter<T>.
• Exercise standalone reader and writer registrations in a working host.
• Verify singleton and factory-invocation behavior according to the intended contract. Tracing wrappers may be different objects, but must use the intended underlying store.
• Verify the documented behavior when registrations already exist or registration methods are called more than once.

Acceptance criteria

• The tracing/registration-overload combinations are covered with actual event writes and reads.
• Reader, writer, and store interfaces observe consistent backing-store state where registered as one store.
• Factory invocation counts and service lifetimes match the intended singleton contract.
• Existing-registration behavior is explicitly tested and documented.
• Any process-wide diagnostics settings are restored after each test and isolated from parallel tests.
• Tests use a stateful in-memory store and require no Docker containers.

Validation

Run the dependency-injection test project and collect focused coverage for store registrations. Add a regression test before correcting any inconsistency discovered by the host-level tests.