White Box Testing vs. Black Box Testing for Software Quality Assurance
Black box tests and white box tests offer two different ways to test the software. While one is not inherently “better” than the other, both forms have specific pros and cons that must be weighed against the needs of the evaluator. These two forms are not mutually exclusive and the “gray box tests” adopt characteristics of both.
Black box quality testing software uniquely verifies results in a way that does not require programming knowledge or understanding of software code. In this form of results-based testing, the evaluator simply knows that a certain input must produce the corresponding output; the tester does not understand how the software actually creates the output. Some typical test methods include state transition tables, limit value analysis, and error guessing.
The strengths and weaknesses of black box testing depend on the simplicity of results-based testing and the lack of the necessary technical knowledge. In short, it is simpler to implement, but that simplicity limits the scope of testing. Most programs have thousands, if not millions of inputs, making it virtually impossible to test every input / output. Because no specialized knowledge is required, it is easier and cheaper to create test kits. Still, regular software changes tend to break these tests due to their reliance on a stable interface, which can prolong testing and increase costs. Finally, black box quality testing has the potential for greater objectivity because all testing is done from the user’s point of view; the designer is rarely part of the process.
A software white box test verifies the inner workings of what is being tested. It requires in-depth knowledge of software code, as well as the programming skills necessary to repair errors. Some examples of white box testing include mutation testing, code coverage, and fault injection.
White box quality tests are much more efficient than black box tests when debugging programming code. White-box testers will find bugs more quickly due to their practical knowledge of the software, but this experience and training adds to the cost. This cost can be met with automated testing of isolated areas of programming code. White-box tests also struggle to test common user unpredictable behavior. You can only try advance tickets; these typically do not include the experimental or ill-conceived ideas of the average person.
With large teams, extensive testing of any software generally incorporates both types; This is called a gray box or layered test. Gray box quality testing often involves a black box group submitting bug reports to a white box team, or a white box group validating bug fixes through input from other testers.
The question of whether to use black box, white box, or gray box testing can only be answered when developers consider their needs, budget, and the complexity of their software. Still, almost all contemporary software development uses gray box quality testing as a natural part of the alpha and beta release process.