csharp-mstest.prompt.md

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description	Get best practices for MSTest unit testing, including data-driven tests

MSTest Best Practices

Your goal is to help me write effective unit tests with MSTest, covering both standard and data-driven testing approaches.

Project Setup

• Use a separate test project with naming convention [ProjectName].Tests
• Reference MSTest package
• Create test classes that match the classes being tested (e.g., CalculatorTests for Calculator)
• Use .NET SDK test commands: dotnet test for running tests

Test Structure

• Use [TestClass] attribute for test classes
• Use [TestMethod] attribute for test methods
• Follow the Arrange-Act-Assert (AAA) pattern
• Name tests using the pattern MethodName_Scenario_ExpectedBehavior
• Use [TestInitialize] and [TestCleanup] for per-test setup and teardown
• Use [ClassInitialize] and [ClassCleanup] for per-class setup and teardown
• Use [AssemblyInitialize] and [AssemblyCleanup] for assembly-level setup and teardown

Standard Tests

• Keep tests focused on a single behavior
• Avoid testing multiple behaviors in one test method
• Use clear assertions that express intent
• Include only the assertions needed to verify the test case
• Make tests independent and idempotent (can run in any order)
• Avoid test interdependencies

Data-Driven Tests

• Use [TestMethod] combined with data source attributes
• Use [DataRow] for inline test data
• Use [DynamicData] for programmatically generated test data
• Use [TestProperty] to add metadata to tests
• Use meaningful parameter names in data-driven tests

Assertions

• Use Assert.AreEqual for value equality
• Use Assert.AreSame for reference equality
• Use Assert.IsTrue/Assert.IsFalse for boolean conditions
• Use CollectionAssert for collection comparisons
• Use StringAssert for string-specific assertions
• Use Assert.Throws<T> to test exceptions
• Ensure assertions are simple in nature and have a message provided for clarity on failure

Mocking and Isolation

• Consider using Moq or NSubstitute alongside MSTest
• Mock dependencies to isolate units under test
• Use interfaces to facilitate mocking
• Consider using a DI container for complex test setups

Test Organization

• Group tests by feature or component
• Use test categories with [TestCategory("Category")]
• Use test priorities with [Priority(1)] for critical tests
• Use [Owner("DeveloperName")] to indicate ownership