congiuluc/testing-backend

Backend Testing (.NET)

When to Use

• Creating unit tests for services, validators, or domain logic
• Writing integration tests for API endpoints
• Mocking repository or external service dependencies
• Testing middleware or filters

Official Documentation

• xUnit.net
• Moq Quickstart
• FluentAssertions
• Integration Tests in ASP.NET Core

Core Rule

Every feature must have corresponding tests before it is considered complete.

Procedure

1. Identify test type: unit test (service logic) or integration test (API endpoint)
2. Follow naming conventions in .NET testing reference
3. Review service test sample
4. Use Arrange-Act-Assert pattern for all tests
5. Mock external dependencies at boundaries with Moq
6. Use FluentAssertions for readable assertions
7. Cover: happy path, edge cases, error scenarios, validation
8. Verify tests are deterministic — no external service or time dependencies
9. Run dotnet test locally before committing

Test Structure

tests/
  MyApp.Core.Tests/           # Unit tests for domain logic
  MyApp.Infrastructure.Tests/ # Repository and infra tests
  MyApp.Api.Tests/            # API integration tests

Naming Convention

• Test class: {ClassUnderTest}Tests
• Test method: {Method}_{Scenario}_{ExpectedResult}
• Example: GetByIdAsync_WhenItemExists_ReturnsItem