0 You can’t find defects that don’t exist
Sounds obvious, it is not possible to find a defect if it doesn’t exist no matter how good testing is. But testing is often done in environments that are a cut down version of production, they don’t have all of the interfaces, applications or complete data sets. Yes there are good reasons for this, speed and cost just to name a few. Regularly deploying and testing in an environment that is a replication of production (does not need the same ...