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Gray Box Testing


Is Black Box Testing + White Box Testing = Gray Box Testing?

Gray-box
Testing a system internally and externally i.e. using white box and black box testing approach have their own pros and cons. To overcome the deficiencies & loopholes found in these testing types, a productive blend of white box and black box testing is being developed; Gray Box Testing.

What is Gray Box Testing?

Gray-Box Testing is a combination of black-box testing and white-box testing, which is carried out with the limited or some knowledge and understanding of the internal features, functionality or details of software.

The basic idea behind this type of testing is to have limited access to and understanding of internal features and specifications of a software product for preparing test strategies and test cases, followed by the implementation & executions of these test cases to examine the working of the software product, externally from users-perspective.

What is meant by the black-box and the white-box testing methodologies?

Black-box testing is a methodology of evaluating the functioning of the software, only on the basis of available specifications, and without having knowledge and understanding of the internal features and structure of the software.

Contrary to black-box, white-box testing involves the understanding and usage of internal attributes and structure of the software by the testers to assess the functionality of the software.

Methodology of Gray Box Testing:

white box approach


First step involves the use of white box approach to study and gain the basic understanding of internal structure of the application.

Test Designing


Learnt knowledge and understanding of the application may be used to derive and define the test cases, covering each and every aspect of the application.


black box approach


Executions of developed test cases using black box testing approach to externally the test the software application qualities.

If black-box and white-box, then why to go for gray-box?

Gray-box provides the straightforward approach to get benefited with the unique blend of black-box and white-box testing features through a single testing technique. Through black-box and white-box methods, it is difficult to trace the issues pertaining to end-to-end data flow, but can be achieved easily through gray-box testing.

productive blend of black box and white box


List of Gray Box Testing Techniques:

gray box techniques


  • Matrix Testing

    It involves the examination of intrinsic risks, particularly business and technical risks, linked with the variables, defined by the developers in the software program.

  • Regression Testing

    It involves, repeatedly testing of software, after each modification in the software or its module, to ensure that these changes do not obstructs the existing functionality of the software. Read more of it in our article on regression testing

  • Pattern Testing

    Pattern testing is all about the usage of analysis of previous defects to carry out the testing, by just going through the code. These analyses may consist of considerable and specific reasons for the bug/defect.

  • Orthogonal Array Testing

    It is a black-box testing type technique, implemented by Taguchi that approaches statistical and organized way of software testing, to locate defective logics in the system. It is generally, used when there are lesser number inputs for the software under test, but are too large and complex, for carrying out exhaustive testing. Refer to our article orthogonal array testing to access complete insight to this testing.

Features of Gray Box Testing:

  • It is a combination of black-box and white-box testing.
  • Also known by the name of translucent testing.
  • Gray box acts as a bridge between the black-box and white-box testing.
  • "Complete white-box testing is not possible".
  • Gray box testing is very much effective for web-application testing, business domain testing, distributed environment and security assessments.
  • Unbiased type of testing due to maintenance of boundary between developers and testers.
  • User-perspective is being considered for carrying out the testing.
  • Knowledge of internal features is being restricted to data and documents, pertaining to design, UML and system architecture.
  • Gradual increase in the knowledge may expose more loopholes present in the software.
  • Due to availability of limited knowledge, test coverage depends upon skills of the testers to generate exceptional testing scenarios.
  • Although, applicable to all levels of testing but mostly useful for integration testing.
  • Gray box is ineffective for algorithm testing.
  • It can be performed by the end-users as well as by the testers and the developers also.
"Software testing is a complex and time-taking activity, and still, it is not possible to estimate the scope of testing. Gray-box testing provides a powerful approach, to test the software product externally, on the basis of its internal working."