Code integrity refers to a developer's confidence in the correctness of their code, encompassing various correctness-checking processes and metrics such as automated testing, code review, and AI-based analysis. While automated tests are a common method for increasing confidence, they alone do not guarantee code integrity. Code coverage techniques like line coverage, branch coverage, and mutation testing provide metrics to increase confidence but have limited correlation with real code integrity. Shift-left testing moves testing earlier in the development pipeline, but expand-right code integrity expands this concept to include broader correctness-checking processes and their metrics, allowing developers to control more of the project's unit testing and integration phases, ultimately leading to a combination of shift-left and expand-right approaches for achieving code integrity in modern software systems.