What is white box testing

What is White Box Testing and how is it used?

Software testing is a process used in evaluating software quality. Testing makes its presence felt in almost every software development project, and product launches depend a lot on testing reviews these days. During the Testing Cycle, the software undergoes thorough testing to identify bugs and errors.

There are several testing techniques that testers can use to cover different types of testing. White box and black box testing are two commonly heard terms when we talk about testing methods. This post covers what white box testing is, the techniques used, and finally some advantages and challenges for testers when using this testing method.

How does White Box Testing help?

White box testing involves testing software by checking the code. Unlike Black Box Testing, where the tester’s focus is primarily on specification testing and what the system is expected to do, white box testing examines how the application has been created. It explores how the software can meet the anticipated requirements by testing its internal workings rather than the look and feel.

White box testing is an effective level of testing because it improves the code’s efficiency by ensuring it is up to the standards, adheres to security protocols, and identifying any run-time errors during the early stages of development. The testing does not depend on the GUI, so developers value this testing model highly. The types of activities involved in this type of testing are also called Structural Testing or Open Box Testing. The term open box or white box indicates that the testing delves within the software’s box into the application’s design and internal workflows.

What is white box testing

While the white box testing technique is used during the unit testing phase, it is also used for other phases like Integration, System, and Regression Testing. White box testers have access to the code, and sometimes upon encountering an issue, the testers proceed with the fix themselves.

How to Conduct White Box Testing

The same test procedure steps that apply to manual testing are used in white box testing. This means that a tester already knows the requirement, understands test case creation, and how to perform test execution, but these vary slightly for this type of testing.

Every white box tester should be well versed in the source code. Test scripts creation depends on the scope of the testing. Some of the commonly used white box techniques are:

  • Statement Coverage: ensures that every statement is executed at least once. This method employs the conversion of source code to control flow graphs. The graphs help in determining the control points.
  • Branch Coverage: helps validate all the branches, including the If-Else and Conditional loops. In branch coverage, the execution of each statement is not the focus, but it is instead, where decisions are implemented. Testing covers both possible outcomes, such as TRUE and FALSE.
  • Conditions Coverage: An application may have single or multiple conditions for driving a decision. Because considering every situation for testing is impossible, the team usually determines the condition’s complexity and then uses this information to define the test scripts.
  • Path Coverage: A path is a sequence of events such as executable statements of an application from entry to an exit point. In path coverage, the testers make sure to verify every path.

White Box Testing Challenges

White box testing offers a number of benefits to testers, such as code optimization and being able to identify security loopholes, but the method is still not the most preferred testing method. There are certain limitations and challenges which make this technique less frequently used than black box testing.

  1. Complex and costly: White Box testing can be a complicated and expensive procedure requiring testers to have programming knowledge. The tester needs to upgrade their technical skills regularly to maintain their standing in the face of the changing conditions. Whenever code changes, a massive effort is required in this type of testing to update the test scripts.
  2. Difficulty in obtaining resources: This form of testing requires specific skills, unlike black box testing, which means that while cross-functional testers can be utilized for black box, this is not the case with this type of testing, making it more difficult to share resources within these projects.
  3. Lengthy and time-consuming: White box testing requires executing every code of the test object at least once. It is more suitable when the application uses personal information, demanding stronger accountability, where even a single defect can lead to massive loss and impact on the overall business.
  4. Pros and cons of coverage: This method helps with discovering any program or function errors, but there is a high probability of omitting coverage from a requirements perspective. It helps in code optimization but cannot guarantee that all requirements have been implemented.


Each testing method comes with pros and cons, and software testing cannot utilize all available testing methods for every test case. Choosing either black box, white box, or both types of testing depends on the nature of the project, the timeline, and estimated cost, but both have the capacity to help improve the end product.

Priya Rani

Priya Rani

An Enthusiastic QA Expert who loves to share knowledge and experience through blogging.