In my experience, complicated rules like this are extremely unreliable. Claude just ignores it much of the time. The problem is that when Claude sees a failing test it is usually just an obstacle to completing some other task at hand - it essentially never chooses to branch out into some new complicated workflow and instead will find some other low friction solution. This is exactly why subagents are effective: if Claude knows to always run tests via a testing subagent, then the specific testing workflow can become that subagent’s whole objective.