How does it handle repository dependencies?

It recommends mocking repository interfaces to assert that the correct methods are called with the right domain objects, ensuring tests are fast and side-effect free.

What layers does this skill cover?

It primarily focuses on the inner layers of an application: the Domain layer (Entities and Value Objects) and the UseCase layer (Application Services).

Do I need a specific testing library?

This skill is optimized for use with pytest and Python's built-in unittest.mock library, specifically leveraging the Mock(spec=...) pattern.

Is this compatible with other frameworks?

While the skill is tailored for FastAPI and DDD, the architectural testing patterns are highly applicable to any Python project following Clean or Hexagonal Architecture.

Does it include API or integration tests?

While it provides the structure for infrastructure and presentation tests, its primary focus is on unit testing business logic to ensure strict decoupling from external systems.

FastAPI DDD Testing Suite

Name: FastAPI DDD Testing Suite
Author: iktakahiro

byiktakahiro

0•

Security & Testing

Guides unit testing for Python applications using FastAPI and Domain-Driven Design by providing structured patterns for domain and use case layers.

This skill provides comprehensive guidance for implementing unit tests within the Domain and UseCase layers of a Python FastAPI application following Onion Architecture principles. It helps developers maintain pure business logic by testing Value Objects and Entities without mocks, while orchestrating robust UseCase tests using repository interface mocking via pytest. By focusing on inner-layer integrity and state transitions, it ensures that core business rules remain verified and decoupled from external infrastructure, mirroring the proven dddpy reference architecture.

Key Features

01Guidance for testing business rule invariants and state transitions

02Standardized folder structure for DDD testing (Domain, UseCase, Infrastructure)

03UseCase testing strategies using unittest.mock and repository interfaces

04Domain layer testing patterns for Value Objects and Entities without mocks

05Integration with pytest for fast, isolated test execution

060 GitHub stars

Use Cases

01Structuring a new FastAPI project's test directory according to Onion Architecture

02Creating unit tests for complex business logic in DDD Entities and Value Objects

03Mocking repository interfaces to isolate application service logic in UseCase tests

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add iktakahiro/python-fastapi-ddd-skill python-fastapi-ddd-testing-skill

For use in Claude.ai and ChatGPT

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