testing

Integration testing in .NET 10 uses WebApplicationFactory to validate the HTTP pipeline and Testcontainers to provision real PostgreSQL or SQL Server databases, catching SQL and transaction issues. This replaces in-memory databases with real infrastructure for reliable test results.

In-memory databases for .NET integration tests miss real SQL constraints, transaction behaviors, and provider-specific quirks. Using Testcontainers with actual PostgreSQL or SQL Server containers provides high-value verification matching production behavior, preventing misleading test outcomes.

Testing time-dependent logic in xUnit v3 uses TimeProvider and FakeTimeProvider patterns to control time deterministically. This ensures reliable assertions for scheduled tasks or temporal business logic without relying on system clocks or artificial delays.

The best way to structure xUnit v3 tests is enforcing strict Arrange-Act-Assert separation while avoiding implementation-detail assertions. This approach focuses on observable behavior and higher-signal verification using snapshot testing with Verify and deterministic test data builders.

Snapshot testing with Verify works for .NET 10 integration tests by capturing and validating complex outputs against baseline files. Combined with deterministic test data builders, it provides higher-signal verification and reduces brittle implementation-detail assertions.

WebApplicationFactory tests routing, validation, business logic, and persistence in .NET 10 by configuring a realistic test host. It validates the full HTTP pipeline end-to-end, ensuring integration tests accurately reflect production request handling behavior.