White box testing, also known as clear box testing, transparent box testing, or structural testing, is a method of software testing that tests internal structures or workings of an application, as opposed to its functionality. In this type of testing, an internal perspective of the system, as well as programming skills, are used to design test cases. The tester chooses inputs to exercise paths through the code and determines the appropriate outputs.
White box testing involves the detailed investigation of internal logic and structure of the code. It is also known as glass testing or open box testing. In order to perform white box testing on an application, a tester needs to know the internal workings of the code.
The tester needs to have a look inside the source code and find out which unit/units of the code are behaving inappropriately. This method of testing is applicable at the unit, integration, and system levels of the software testing process. It is usually performed by the developers who know the ins and outs of the code they have written.
There are several types of white box testing, each with its own specific focus and purpose. These include:
Statement coverage is a type of white box testing that ensures that every line of code in the program has been executed at least once. This type of testing is used to find bugs in the code and to ensure that all lines of code are working as expected.
Statement coverage is a useful tool for identifying areas of the code that have not been tested. However, it does not guarantee that all paths through the code have been tested, nor does it ensure that all possible inputs have been tested.
Decision coverage, also known as branch coverage, is a type of white box testing that ensures that each decision point in the code (such as an if statement) has been executed for both true and false conditions. This type of testing is used to find bugs in the decision-making parts of the code.
Decision coverage is a more thorough form of testing than statement coverage, as it ensures that all decision points have been tested. However, like statement coverage, it does not guarantee that all paths through the code have been tested.
Path coverage is a type of white box testing that ensures that all paths through the code have been executed. This includes all possible combinations of true and false conditions in decision points.
Path coverage is the most thorough form of white box testing, as it ensures that all paths through the code have been tested. However, it can be time-consuming and complex to implement, especially in large or complex programs.
White box testing offers several advantages over other types of software testing. These include:
Despite its advantages, white box testing also has some disadvantages. These include:
White box testing is a powerful tool for improving the quality of software. By testing the internal workings of the code, it can catch errors and bugs that other types of testing might miss. However, it also has its disadvantages, including complexity, the potential to miss certain issues, and cost.
Despite these disadvantages, the benefits of white box testing make it a valuable part of the software development process. By understanding the principles and techniques of white box testing, software developers and testers can create more reliable, high-quality software.