One of the fundamental characteristics of unit tests is that they should be independent of other system components. This means that a unit test should only cover the functionality of a single component or unit of code, without relying on or interacting with external systems or modules. This independence ensures that the tests are focused, reliable, and can be run quickly, providing immediate feedback on the code quality of the unit being tested.
References = The ISTQB Advanced Level Agile Technical Tester documents outline the importance of unit test independence as a key aspect of technical testing in an Agile context. This characteristic is crucial for maintaining the effectiveness and efficiency of the testing process within Agile development cycles1.