There are mainly four Levels of Testing in software testing
A Unit is a smallest testable portion of system or application which can be compiled, liked, loaded, and executed. This kind of testing helps to test each module separately.
The aim is to test each part of the software by separating it. It checks that component are fulfilling functionalities or not. This kind of testing is performed by developers.
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Levels of testing /article/eng
Unit testing /article/eng
Unit testing /article/rus
Unit testing /video tutorial/eng
Unit testing /video tutorial/arm