The Methods of Software Testing

Black Box Testing

This method gets its name because a QA engineer focuses on the inputs and the expected outputs without knowing how the application works internally and how these inputs are processed. The purpose of this method is to check the functionality of the software making sure that it works correctly and meets user demands. This method can be applied to any testing level but is used mostly for system and user acceptance testing.

White Box Testing

Unlike black box testing, this method requires profound knowledge of the code as it entails testing of some structural part of the application. Therefore, generally, the developers directly involved in writing code are responsible for this type of testing. The purpose of white box testing is to enhance security, the flow of inputs/outputs through the application, and to improve design and usability. This method is mainly used at the unit and integration testing levels.

Grey Box Testing

This method is a combination of the previous two, since it involves testing of both functional and structural parts of the application. Using this method, an experienced tester has partial knowledge of the internal application structure and based on this knowledge can design test cases while still testing from the black-box perspective. This method is mostly applicable to the integration testing level.

Ad Hoc Testing

This is an informal testing method as it’s performed without planning and documentation. Conducting tests informally and randomly without any formal, expected results, the tester improvises the steps and arbitrarily executes them. Though defects found with this method are more difficult to reproduce given the absence of written test cases, this approach helps find important defects quickly, something which cannot be done with formal methods.