Developer Documents How AI-Generated Tests Faked 20 Passing Checks in Three Days

A software tooling developer catalogued every self-caused false positive they encountered during the week of 7 September 2026, finding 20 green checkmarks that did not reflect genuine passes. Common failure patterns included checkers returning success when they scanned zero items, grep queries matching irrelevant or misleading content, and timestamps copied from file modification dates rather than actual verification. In one case, a leak checker passed a document because it measured the wrong axis entirely, missing the real category of risk. Pipeline errors caused by shell commands silently failing also reported zero results instead of signalling an unknown state. The developer concluded that a failed or empty measurement should never be treated as a pass, and that any limitation not surfaced in tool documentation is effectively hidden from users.