Dart Test Fundamentals

Covers the fundamentals of package:test in Dart: how to structure tests with test and group blocks, lifecycle methods like setUp and tearDown, and configuration through dart_test.yaml. The guidance on addTearDown versus try-finally for resource cleanup is solid and will prevent messy test code. It also includes practical naming conventions (like using PascalCase for class-based groups) and sensible advice about avoiding redundant wrapping. The note about not removing single groups during cleanup unless asked is refreshingly honest about diff churn. Use this when you're setting up test files from scratch or need to refactor an existing test suite's structure.