Mobile SDK testing is distinct from mobile app testing, as it involves ensuring the SDK's core functionality operates seamlessly with minimal impact on the host app's UI, UX, and performance. While mobile app testing focuses on functional, environment, and non-functional testing to ensure the app works as expected, SDK testing demands a higher quality standard due to its integration into various apps targeting a wide range of devices and OS versions. Challenges include maintaining stability, ensuring easy integration for developers, and adapting to different locales and environments without negatively affecting resource consumption or other SDKs in the host app. An effective SDK should enhance the host app's features unobtrusively, behaving as an integral part of the app rather than as third-party code.