In a non-technical role, the definition of something being “done correctly” ends when the output/result matches the requirements. Whether that be a user experience, reporting, or whatever the requirements are. As long as those are clearly defined, and you can test the application against those definitions, the trust lies in the development team that it was programmed properly.

Any kind of testing should be defined at a high level. What is being tested and what is the expected result? What should trigger an alert?