Blog

Mert Özen's blog posts on software development, backend, frontend, and DevOps.

Series

.NET Core Web API 36 Angular 31 JavaScript Basics 19 JavaScript Intermediate 18 JavaScript Advanced 16 TypeScript Basics 14 TypeScript Intermediate 14 TypeScript Advanced 12 Entity Framework Core 28 Dapper 16 Git & GitHub 29 Web Security (OWASP Top 10) 21 LLM Fundamentals 20 C# Fundamentals 20 Object-Oriented Programming in C# 16 C# Collections and Generics 11 LINQ 17 Asynchronous Programming in C# 17 Advanced C# 14 C# Versions 6 Solution Patterns 22 SOLID and Design Principles 12 Clean Code 13 Design Patterns 23 UML and Modeling 18 Introduction to Software Architecture 9 Clean, Onion and Hexagonal Architecture 8 Vertical Slice Architecture 6 Domain-Driven Design 12

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Software Architecture PART 05

Testing Vertical Slices: Integration Tests per Slice and Unit Tests Where They Matter

A slice's natural test unit is the path from the HTTP request to the real database, while domain rules are tested cheaply with pure unit tests. We build per-slice tests with WebApplicationFactory, a real SQL Server via Testcontainers, and Respawn, and show with real output how tests break each other without a reset and how the InMemory provider both passes and fails wrongly on the same search query.

7 Nov 2026 11 min 2

Software Architecture PART 08

Testing and Protecting Clean Architecture: Core Tests, Adapter Tests, and Architecture Tests

In Clean Architecture you test the core without a database using in-memory adapters, test the adapters against the production SQL Server with Testcontainers, and make the Dependency Rule unbreakable in CI with ArchUnitNET rules. The decimal precision problem SQLite hid, violations the compiler misses, the trap of a rule that selects nothing without Types(true), and a note that NetArchTest hasn't been updated since 2021.

7 Nov 2026 16 min 8