Csharp Xunit

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 [Theory] combined with data source attributes
• Use [InlineData] for inline test data
• Use [MemberData] for method-based test data
• Use [ClassData] for class-based test data
• Create custom data attributes by implementing DataAttribute
• Use meaningful parameter names in data-driven tests

Assertions

• Use Assert.Equal for value equality
• Use Assert.Same for reference equality
• Use Assert.True/Assert.False for boolean conditions
• Use Assert.Contains/Assert.DoesNotContain for collections
• Use Assert.Matches/Assert.DoesNotMatch for regex pattern matching
• Use Assert.Throws<T> or await Assert.ThrowsAsync<T> to test exceptions
• Use fluent assertions library for more readable assertions

Mocking and Isolation

• Consider using Moq or NSubstitute alongside XUnit
• 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 [Trait("Category", "CategoryName")] for categorization
• Use collection fixtures to group tests with shared dependencies
• Consider output helpers (ITestOutputHelper) for test diagnostics
• Skip tests conditionally with Skip = "reason" in fact/theory attributes