Phase Injected indicates the phase in the software development lifecycle where the bug was introduced. Phase Injected is always earlier in the software development lifecycle than the Phase Detected. Phase Injected can be known only after a proper root-cause analysis of the bug.

Can defects be injected in testing phase?

We have found that even using a rigorous PSP development process, nearly a quarter of all defects injected will escape into unit test. Moreover, finding and removing defects in unit test required seven times as much effort as removing them in earlier phases.

Which stage determines defects?

A tester should start identifying defects from the requirement collection stage. This should be executed through the analysis and design stage as well. Proceeding from the Design stage, Integration testing cases and Unit test cases should be completed.