dotnet-integration-testing

Integration testing patterns for .NET applications using WebApplicationFactory, Testcontainers, and .NET Aspire testing. Covers in-process API testing, disposable infrastructure via containers, database fixture management, and test isolation strategies.

Version assumptions: .NET 8.0+ baseline, Testcontainers 3.x+, .NET Aspire 9.0+. Package versions for Microsoft.AspNetCore.Mvc.Testing must match the project's target framework major version (e.g., 8.x for net8.0, 9.x for net9.0, 10.x for net10.0). Examples below use Testcontainers 4.x APIs; the patterns apply equally to 3.x with minor namespace differences.

Out of scope: Test project scaffolding (creating projects, package references) is owned by [skill:dotnet-add-testing]. Testing strategy and test type selection are covered by [skill:dotnet-testing-strategy]. Snapshot testing for verifying API response structures is covered by [skill:dotnet-snapshot-testing].

Prerequisites: Test project already scaffolded via [skill:dotnet-add-testing] with integration test packages referenced. Docker daemon running (required by Testcontainers). Run [skill:dotnet-version-detection] to confirm .NET 8.0+ baseline.

Cross-references: [skill:dotnet-testing-strategy] for deciding when integration tests are appropriate, [skill:dotnet-xunit] for xUnit fixtures and parallel execution configuration, [skill:dotnet-snapshot-testing] for verifying API response structures with Verify.

WebApplicationFactory

WebApplicationFactory<TEntryPoint> creates an in-process test server for ASP.NET Core applications. Tests send HTTP requests without network overhead, exercising the full middleware pipeline, routing, model binding, and serialization.

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