Milan Jovanović • 7/11/2026

How to Test Vertical Slice Architecture

This article addresses common questions about testing vertical slice architecture (VSA), explaining why traditional mocking and layered testing approaches don't apply. It advocates testing the entire slice as a unit—from endpoint to database—using real infrastructure via WebApplicationFactory and Testcontainers. The setup includes a shared fixture booting Postgres in Docker, with examples for handling fake external services. It emphasizes that slice tests catch SQL, mapping, validation, and routing issues that mocked unit tests miss, making the test pyramid irrelevant for VSA codebases.

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#integration testing #Database Testing #Vertical Slice Architecture