Tdd Architecture Patterns

TDD Architecture Patterns

Software architecture should enable testing, not hinder it. These patterns ensure your system remains decoupled and verifiable.

Core Patterns

1. Hexagonal Architecture (Ports & Adapters)

• Keep your business logic (the Core) isolated from external concerns (DB, UI, APIs).
• Use Ports (interfaces) for the core to communicate with the outside world.
• Use Adapters to implement those ports for specific technologies.

2. Dependency Injection (DI)

• Invert the control of dependencies. Instead of a class creating its helper, it receives it via a constructor or parameter.
• Benefit: Allows you to easily swap real dependencies with mocks in tests.

3. SOLID Principles

• S: Single Responsibility.
• O: Open/Closed (Open for extension, closed for modification).
• L: Liskov Substitution.
• I: Interface Segregation.
• D: Dependency Inversion.

Guidelines

• Avoid Global State: It makes tests non-deterministic and hard to run in parallel.
• Keep Logic Pure: Prefer stateless functions where possible; they are the easiest to test.
• Test-First Design: If a feature is hard to test, it usually means the architecture is too tightly coupled.