Achieving full code coverage does not guarantee that the component or system is fully tested or free of defects. Code coverage metrics indicate the extent to which the source code has been tested, but they do not account for the quality of the tests or whether all possible scenarios have been considered. Other types of testing, including functional, performance, and security testing, are necessary to ensure comprehensive testing.
The ISTQB CTFL Syllabus v4.0 highlights that while high code coverage is beneficial, it does not equate to complete testing.