Testing .NET code with MSTest, from domain events to HTTP, explained in depth, one at a time.
Test the aggregate with no infrastructure, the SaveChanges interceptor and the outbox on SQLite in memory, and an idempotent consumer, with MSTest 4, hand-written fakes and a mutation check.
One MSTest project per layer: domain tables with DataRow, use cases against a fake port, the HTTP contract with WebApplicationFactory, and a test for the dependency rule itself.