---

name: testing-strategy description: Generate tests following project conventions. Use when writing unit tests, integration tests, creating test fixtures, or implementing test builders. Triggers on requests like "write tests for", "add test coverage", "create test builder", "test this handler", or "implement tests".

Testing Strategy

Generate and maintain tests following project-specific conventions for this .NET/EF Core DDD codebase.

Quick Reference

Test Pyramid

        +-------------+
        |  App Layer  |  Primary: Integration tests with SQLite in-memory
        |  Handlers   |  IAsyncLifetime pattern for isolation
        +-------------+
        |  Domain     |  Secondary: Unit tests for complex logic only
        |  Logic      |  Skip simple getters/setters
        +-------------+

Key Decisions

• NO E2E tests - Application layer integration tests provide sufficient coverage
• SQLite in-memory - Not EF Core InMemory provider (real constraints matter)
• IAsyncLifetime - Each test method gets fresh DB instance
• Builder pattern - Fluent builders with sensible defaults
• Japanese test names - Describe behavior clearly

Test Implementation Guide

Step 1: Determine Test Type

Layer	Test Type	When to Test
Application (CommandHandler)	Integration	Always
Application (QueryHandler)	Integration	Always
Domain (Aggregate)	Unit	Complex state transitions only
Domain (Service)	Unit	Complex business rules only
Infrastructure	Skip	Covered by Application tests

Step 2: Create Test Class

See references/patterns.md for complete templates:

• Application Layer: IAsyncLifetime pattern with SQLite
• Domain Layer: Simple unit test class

Step 3: Use Builders for Test Data

See references/builders.md for all available builders.

Key rules:

• Single entity: use defaults
• Multiple entities: MUST specify unique IDs

Step 4: Write Test Methods

See references/examples.md for common scenarios:

• CommandHandler tests
• QueryHandler with related data
• Domain state transitions
• Exception testing

Resources

File	Content
patterns.md	Templates, builders, examples, anti-patterns
packages.md	NuGet packages and xUnit config

Anti-Patterns Summary

Anti-Pattern	Correct Approach
Shared DbContext	IAsyncLifetime with fresh DB
Constructor init	InitializeAsync per test
Default IDs for multiple entities	Explicit ID per entity
Testing simple getters	Only test complex logic
E2E tests	Application layer integration