unit-testing

name: unit-testing description: Unit testing patterns for .NET applications using EF Core In-Memory Provider, AAA structure, test data helpers, and TDD workflows. Use when writing unit tests for Application Services, domain logic, or data access.

Unit Testing Patterns for .NET

Unit testing patterns for .NET applications covering test structure, EF Core in-memory database setup, test data helpers, and TDD workflows.

GloboTicket Architecture Context

Application Services Location: GloboTicket.Application/Services/

• Application Services inject base DbContext class (not concrete GloboTicketDbContext)
• Use _dbContext.Set<TEntity>() for data access instead of specific DbSets
• Inject ITenantContext from GloboTicket.Application.MultiTenancy
• Unit tests use EF Core In-Memory Provider to test services without Infrastructure dependencies

TDD Philosophy

TDD is about unit tests only. Unit tests drive implementation using EF Core In-Memory Provider for fast, isolated testing.

Integration tests follow implementation. They use real databases to verify migrations, complex queries, and system integration.

Test Structure

• AAA Pattern: Arrange-Act-Assert with Given-When-Then comments
• Test Naming: MethodName_Scenario_ExpectedBehavior
• Given-When-Then Comments: Describe test flow and intent

EF Core In-Memory Database Setup

Use EF Core In-Memory for all unit-test data access; avoid mocking data stores. Load patterns/ef-core-in-memory-setup.md when:

• Configuring DbContext and ITenantContext for tests
• Ensuring per-test database isolation and async disposal
• Understanding provider limitations (e.g., navigation-property filters)

Multi-Tenancy Testing

Direct Tenant Filtering (works in unit tests): Entities with direct TenantId properties

Navigation Property Filtering (integration tests only): EF Core In-Memory does NOT support query filters using navigation properties.

For child entities filtered through navigation properties:

• Unit Tests: Focus on business logic (validation, transformations, error handling)
• Integration Tests: Test tenant isolation with real database

For setup, patterns, and limitations, load patterns/ef-core-in-memory-setup.md.

Test Data Helper Patterns

Always initialize parent navigation properties (never foreign keys). Require parents for child entities; allow sensible defaults for scalars. Load patterns/test-data-helpers.md when creating Given helpers and structuring required vs optional parameters.

Example Unit Tests

For complete examples that use DbContext + ITenantContext and Given helpers:

• Load examples/service-tests.md for application service tests
• Load examples/domain-tests.md for entity/value object tests

Repository pattern is not used; services access the database via DbContext. Use Given helpers to create root entities and pass required parents to child entities.

Mocking Strategy

• Use in-memory database for repository/service tests
• Mock external dependencies only (email, payment gateways, APIs)
• For mocking examples, load examples/service-tests.md

Best Practices

1. Use AAA Pattern with Given-When-Then comments
2. Follow naming convention: MethodName_Scenario_ExpectedBehavior
3. Initialize navigation properties, never foreign keys
4. Make parent entities required parameters in Given methods
5. Use in-memory database for repository/service tests
6. Mock external dependencies only
7. Focus unit tests on business logic
8. Use integration tests for navigation property tenant isolation
9. Create unique database per test to ensure isolation
10. Always test multi-tenancy when relevant

This approach ensures fast, reliable, and maintainable unit tests that provide confidence in the business logic implementation.

Resources

• .github/skills/unit-testing/patterns/ef-core-in-memory-setup.md
• .github/skills/unit-testing/patterns/test-data-helpers.md
• .github/skills/unit-testing/examples/service-tests.md
• .github/skills/unit-testing/examples/domain-tests.md