csharp-tunit

TUnit Best Practices Your goal is to help me write effective unit tests with TUnit, covering both standard and data-driven testing approaches. Project Setup Use a separate test project with naming convention [ProjectName].Tests Reference TUnit package and TUnit.Assertions for fluent assertions Create test classes that match the classes being tested (e.g., CalculatorTests for Calculator ) Use .NET SDK test commands: dotnet test for running tests TUnit requires .NET 8.0 or higher Test Structure No test class attributes required (like xUnit/NUnit) Use [Test] attribute for test methods (not [Fact] like xUnit) Follow the Arrange-Act-Assert (AAA) pattern Name tests using the pattern MethodName_Scenario_ExpectedBehavior Use lifecycle hooks: [Before(Test)] for setup and [After(Test)] for teardown Use [Before(Class)] and [After(Class)] for shared context between tests in a class Use [Before(Assembly)] and [After(Assembly)] for shared context across test classes TUnit supports advanced lifecycle hooks like [Before(TestSession)] and [After(TestSession)] Standard Tests Keep tests focused on a single behavior Avoid testing multiple behaviors in one test method Use TUnit's fluent assertion syntax with await Assert.That() Include only the assertions needed to verify the test case Make tests independent and idempotent (can run in any order) Avoid test interdependencies (use [DependsOn] attribute if needed) Data-Driven Tests Use [Arguments] attribute for inline test data (equivalent to xUnit's [InlineData] ) Use [MethodData] for method-based test data (equivalent to xUnit's [MemberData] ) Use [ClassData] for class-based test data Create custom data sources by implementing ITestDataSource Use meaningful parameter names in data-driven tests Multiple [Arguments] attributes can be applied to the same test method Assertions Use await Assert.That(value).IsEqualTo(expected) for value equality Use await Assert.That(value).IsSameReferenceAs(expected) for reference equality Use await Assert.That(value).IsTrue() or await Assert.That(value).IsFalse() for boolean conditions Use await Assert.That(collection).Contains(item) or await Assert.That(collection).DoesNotContain(item) for collections Use await Assert.That(value).Matches(pattern) for regex pattern matching Use await Assert.That(action).Throws() or await Assert.That(asyncAction).ThrowsAsync() to test exceptions Chain assertions with .And operator: await Assert.That(value).IsNotNull().And.IsEqualTo(expected) Use .Or operator for alternative conditions: await Assert.That(value).IsEqualTo(1).Or.IsEqualTo(2) Use .Within(tolerance) for DateTime and numeric comparisons with tolerance All assertions are asynchronous and must be awaited Advanced Features Use [Repeat(n)] to repeat tests multiple times Use [Retry(n)] for automatic retry on failure Use [ParallelLimit] to control parallel execution limits Use [Skip("reason")] to skip tests conditionally Use [DependsOn(nameof(OtherTest))] to create test dependencies Use [Timeout(milliseconds)] to set test timeouts Create custom attributes by extending TUnit's base attributes Test Organization Group tests by feature or component Use [Category("CategoryName")] for test categorization Use [DisplayName("Custom Test Name")] for custom test names Consider using TestContext for test diagnostics and information Use conditional attributes like custom [WindowsOnly] for platform-specific tests Performance and Parallel Execution TUnit runs tests in parallel by default (unlike xUnit which requires explicit configuration) Use [NotInParallel] to disable parallel execution for specific tests Use [ParallelLimit] with custom limit classes to control concurrency Tests within the same class run sequentially by default Use [Repeat(n)] with [ParallelLimit] for load testing scenarios Migration from xUnit Replace [Fact] with [Test] Replace [Theory] with [Test] and use [Arguments] for data Replace [InlineData] with [Arguments] Replace [MemberData] with [MethodData] Replace Assert.Equal with await Assert.That(actual).IsEqualTo(expected) Replace Assert.True with await Assert.That(condition).IsTrue() Replace Assert.Throws with await Assert.That(action).Throws() Replace constructor/IDisposable with [Before(Test)] / [After(Test)] Replace IClassFixture with [Before(Class)] / [After(Class)] Why TUnit over xUnit? TUnit offers a modern, fast, and flexible testing experience with advanced features not present in xUnit, such as asynchronous assertions, more refined lifecycle hooks, and improved data-driven testing capabilities. TUnit's fluent assertions provide clearer and more expressive test validation, making it especially suitable for complex .NET projects.