I (very briefly) worked in a startup whose business was search (on a certain domain) and they had no tests for their "Search.java" file (the real name was 300x

I (very briefly) worked in a startup whose business was search (on a certain domain) and they had no tests for their "Search.java" file (the real name was 300x longer, because java devs…). I had found some operations to tweak the scoring, except that some were multiplications by one, so I removed them. But I got told to not touch them because they wouldn't know if I had broken it until some customer complained. The CTO told me off for my completely irresponsible behaviour.