Test suites are one leg of the stool. The others include memory safety, type safety and (for real-time applications) resource guarantees, as well as a formal de

Test suites are one leg of the stool. The others include memory safety, type safety and (for real-time applications) resource guarantees, as well as a formal development process that includes rigorous code inspections. Put everything together and you have "space shuttle computer" level investment required. As you give up legs, the stool becomes cheaper yet not as sturdy.