In the process of application creation always appear some defects or bugs that can result in very different consequences depending on the stage when they actually appeared. Usually, any application lifecycle is following the next plan: requirements, architecture or design, development, software testing and release. In the requirement or planning stage some crucial points can be omitted and a bug is introduced as a result it can lead to its emergence during the whole project. If a defect appears in the design stage, it can mean that the software will not be functional at all. Most quantity of bugs appear in the development stage no matter how professional and qualified the developer is. With the further project progression new defects [...]