csharp-testing

Topics in the source

• C# Testing Patterns
• When to Activate
• Test Framework Stack
• Unit Test Structure
• Arrange-Act-Assert
• Parameterized Tests with Theory
• Mocking with NSubstitute
• ASP.NET Core Integration Tests

Comprehensive testing patterns for .NET applications using xUnit, FluentAssertions, and modern testing practices. Writing new tests for C# code Reviewing test quality and coverage Setting up test infrastructure for .NET projects Debugging flaky or slow tests | Tool | Purpose | |---|---| | xUnit | Test framework (preferred for .NET) | | FluentAssertions | Readable assertion syntax | | NSubstitute or Moq | Mocking dependencies | | Testcontainers | Real infrastructure in integration tests | | WebApplicationFactory | ASP.NET Core integration tests | | Bogus | Realistic test data generation | | Anti-Pattern | Fix | |---|---| | Testing implementation details | Test behavior and outcomes | | Shared mutable test state | Fresh instance per test (xUnit does this via constructors) | | Thread.Sleep in async tests | Use Task.Delay with timeout, or polling helpers | | Asserting on ToString() output | Assert on typed properties | | One giant assertion per test | One logical assertion per test | | Test names describing implementation | Name by behavior: MethodExpectedResultWhenCondition | | Ignoring CancellationToken | Always pass and verify cancellation |