Gray Box Testing

29 Oct 2022
What is Gray Box Testing?
Advantages of Gray Box Testing.
Gray Box Testing Process.
Gray Box Testing Techniques.

What is Gray Box Testing?

A software testing technique in which software testers lack absolute product knowledge and possess only partial information about internal functionality and code of the application software to be tested.
“The software testers are only partially aware of the internal structure of the product to be tested in this technique. But if third-party integration/caching implementation of the product is not transparent, functionality can be tested from the user aspect. So we can proceed with testing without a complete understanding of the internal structure of the product.”
This testing method is a combination of black box testing technique and white box testing technique.
The main aim of this testing technique is to identify bugs resulting from incorrect internal code structure or incorrect usage of the application.
It would be beneficial to use this method in evaluating web applications, executing integration testing, testing distributed environments, and estimating security strength.

Advantages of Gray Box Testing

It combines the capacities of software developers and software testers to improve the overall quality of the application software under test.
Gray box testers need not have in-depth knowledge in software programming to do the testing.
Complex test scenarios or applications can be tested more effectively using this technique.
Software developers are benefited by the usage of this testing method as they get sufficient time to fix the bugs.
Gray box testing is done from both user’s point of view and developer’s point of view increasing the effectiveness of testing.

Gray Box Testing Process

The standard steps to carry out Gray box Testing are as follows:
Identify all of the basic control flows or key paths that should be tested.
Identify important sub-functions that require in-depth testing.
Determine the inputs to be passed to a sub-function.
Determine the outputs that the sub-function is likely to generate for the given inputs.
Develop and execute test cases for this sub-function.
The results produced by the sub-function should be confirmed to be matching with the expected result for the test case.
Repeat steps 2-6 until all identified sub-functions are tested.

Gray Box Testing Techniques

The major techniques for performing gray box testing are matrix testing, regression testing, pattern testing, and orthogonal array testing.
Matrix Testing:-
Involves testing all the variables used in an application software while coding. The technical risks related to the usage of each variable in the code is identified. Every variable is then analyzed based on the identified risks.
  • “This technique discovers unused or un-optimized variables in the program. Unused variables are mostly eliminated from the code”.
Regression Testing:-
In this technique, gray box tests are regularly executed after every change or update made in the code to verify that previously created and tested software still works as desired.
  • “Ensures that a latest code change or bug fix has not impacted any existing functionality of the software”.
Pattern Testing:-
Involves examining the previous version of the application software in order to identify any patterns that caused defects. This helps in revealing the elements that caused the defects and how the irregularities were identified.
  • “The design of gray box test cases can be improved by using this information. This will prevent the occurrence of similar bugs in later versions of the application software under test”.
Orthogonal Array Testing:-
Preferred when maximum code coverage is required with very few test cases and large test data in hand. Uses an organized statistical method of performing tests. This is very helpful in testing complex applications.


  • Gray box testing possesses the advantages of both white box testing and black box testing.
  • It facilitates detecting defects at an earlier stage and preventing these from passing further.
  • Mainly used for functional testing and testing web-based applications.