Watch a 59-minute conference talk from CppCon 2024 where veteran C++ developer Jody Hagins challenges Scott Meyers' famous design guideline by arguing that testability surpasses both ease of use and performance as the most crucial C++ design consideration. Explore the fundamental meaning of testability and its practical importance through rarely discussed aspects that impact software design and implementation. Learn from Hagins' 40 years of C++ experience as he demonstrates why asking "How are we going to test that?" should be the primary question for any software system component. Gain valuable insights into often overlooked elements of testable design while discovering practical techniques to enhance code testability. The presentation includes comprehensive slides and draws from extensive experience in high-frequency trading systems development.