Therefore , it will not catch integration errors or broader system - level errors ( such as functions performed across multiple units , or non-functional test areas such as performance ) .
Additionally , unit testing by definition only tests the functionality of the units themselves .
It will not catch integration errors or broader system - level errors ( such as functions performed across multiple units , or non-functional test areas such as performance ) .
Additionally , unit testing by definition only tests the functionality of the units themselves .