White Box Testing vs Black Box Testing

There are two main types of testing used in software engineering: black box testing and white box testing. In this article, we explore the core differences between white box testing and black box testing and how these differences can impact decisions on which type of testing to use in software development.

By definition:

Black box testing:

Black box testing is used to identify flaws and issues in the security, functional, and behavioral properties of a program by a tester who lacks knowledge in the internal workings of the program or has no access to the internal structures of the program.

White box testing:

White box testing focuses on the internal structural design of an application, which includes the source code of a program. Also known as Clear Box testing, Open Box testing, Transparent Box testing, Structural testing, and Code-Based testing, white box testing requires testers to have access to the source code and have in-depth knowledge of the programming language used in the application. White box testing approach is aimed at functional and behavioral components of a program.

Technical Differences between White Box Testing and Black Box Testing

1. Testing focus: While black box testing focus is on the functional and behavioral features, white box testing focuses on the functional and behavioral components. Black box testing checks for issues from a point of users by engaging with the final product (the program). On the other hand, white box testing checks for programming errors (logic and syntax errors) within the program’s source code.

2. Tester’s knowledge level: A black box tester does not need to have knowledge of the software’s programming language as they won’t be concerned with the internal workings of the software. On the other hand, white box testing requires that the tester have complete and in-depth knowledge of the programming language, software architecture, and design patterns used to build the program.

3. Access level: Black box testing uses both input and output to validate the correctness of an application. The tester has no access to the internal source code of the software. On the other hand, white box testing focuses on the internal components of a software; hence the testers require access to the source code of the application.

4. Testing methods / techniques: The methods available for black box testing include equivalence partitioning, boundary value analysis, and cause and effect graphing. The techniques used in white box testing include statement coverage, branch coverage, decision/condition coverage, basic path testing, loop testing, and data flow testing. These testing techniques are used to design test cases for running the tests.

Black Box Testing vs White Box Testing

While we focussed on the technical, and most critical, differences between black box testing and white box testing in the section above, we will explore more generalized differences between the two.