White Box testing, a type of quality assurance methodology in software testing, focuses on evaluating the internal working of the system. A White Box tester should gain the knowledge of the internals of system and understand how the system is implemented. Once the tester has gained an understanding of the internal structure of the system, he/she can use the knowledge to develop test cases to test the data flow, control flow, information flow, error handling, exceptions, and even coding practices implemented in the system.

Why White Box testing?

White Box testing is carried out to check:

• Security holes in the code
• Broken or incomplete paths in the code
• Flow of the structure mentioned in the specification document
• All conditional loops in the code to verify the complete functionality of the application
• Code line by line or section by section and provide 100% testing

White Box Testing Tools and Techniques

White Box testing is methodological approach of testing the internals of a system by following the below set of activities:

• Understand the system: a White Box tester must carefully go through the requirement document and understand the functional requirements such as how the processing of the data is handled and nonfunctional requirements such as responsiveness.
• Analyze the system: A White Box tester analyzes the technical design and implementation of system by reviewing the technical design and architecture documents.
• Test Design: During test design, a White Box tester utilizes the understanding of the system’s functional/non-functional and technical requirements to create effective test designs by using static & dynamic White Box test design techniques.
• Test Implementation: In this stage, a White Box tester makes use of proven White Box testing frameworks to implement the White Box test cases.

Benefits of White Box testing:

Some important benefits of White Box testing are listed below:

• One of the major benefits of White Box testing is time and cost saving in finding defects which would otherwise require waiting for a Black Box tester to find the issue. This would happen only after the implementation is ready and deployed in the test environment.
• White Box testing not only shows the presence of the defect but also helps in locating the lines of code that caused the defect.
• White Box testing helps in optimization of code.
• White Box testing detects errors that can crop up due to “hidden” code.
• Deciding on which type of input/data should be utilized in testing the application effectively can be easily deduced, as the tester has the knowledge of the internal coding structure.
• It facilitates in removing the extra lines of code which can otherwise cause hidden defects.