Extending MSTest V2

This post details the extensibility points of the MSTest V2 Test Framework API. It explains how developers can extend attributes (e.g., `TestProperty` to strongly-typed attributes), assertions (to be more domain-specific and readable), test execution (at TestMethod and TestClass levels for finer control), and data driving (implementing `ITestDataSource` for custom data sources). The goal is to allow tests to be expressed in language closer to the specific domain model, making the framework more fluent and powerful.