In software testing, the goal is to balance thoroughness with manageability. Unit testing is efficient and manageable, yet it plateaus in effectiveness beyond 70% coverage, a benchmark difficult to achieve in practice. End-to-end (E2E) testing, while comprehensive, becomes increasingly challenging to maintain as software complexity grows, making full coverage impossible. Integration testing is indispensable for ensuring components work together seamlessly, but it also demands more maintenance with software expansion. The key is to strategically combine these testing methods to ensure software quality without overburdening the process, recognizing that more testing doesn't always translate to better outcomes.
“Teams always want to reach high E2E coverage but can’t — and they should reach high unit testing coverage but don’t.“