Gray Box Testing: What is, Techniques, Example - EffectiveSoft
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Gray Box Testing

No development process should proceed without software testing, as it is essential that an application is secure and works properly. To expose any threats, risks, or vulnerabilities affecting an application, gray box testing can be used.
9 min read
Grey Box Testing

    The importance of software quality has grown significantly in recent years due to the increasing dependence on technology in all aspects of business. Ensuring that software products are reliable and operate well is essential to avoid costly errors, mitigate risk, and maintain the trust of users and stakeholders. It is also important to timely identify and address potential issues before they become significant problems. Applying the gray box testing (or grey box testing) approach can enable companies to achieve these objectives.

    This article provides an in-depth look at gray box testing, including an outline of the process and techniques involved as well as the advantages and drawbacks of this approach compared to alternative methods, to help companies understand how gray box testing can be utilized to improve software quality.

    What is gray box testing?

    Gray box is a software testing approach in which a QA specialist with only partial knowledge of an application’s internal structure analyzes both the code operation and the way the application is used. It combines elements of black box and white box testing, offering a balanced approach that allows testers to leverage the strengths and minimize the weaknesses of these alternative assessment methods.

    What is gray box penetration testing: black box + white box
    What is gray box penetration testing: black box + white box

    The key features of gray box testing are as follows:

    • Understanding an application’s underlying technology and architecture.
    • Identifying context-specific issues.
    • Integrating automated and manual testing techniques.
    • Recognizing both practical and technical issues.

    Gray box can be applied to different types of testing, including gray box penetration testing, which provides a security assessment of a particular system component. For example, gray box testing is also used for integration testing, where individual system components are combined and checked in a group, and domain testing, which examines whether each module in a software system accepts inputs within the accepted domain and delivers the required outputs.

    An example of gray box testing

    Gray box testing may be used to assess a web application that contains links to different posts. In this case, the tester checks the following aspects:

    • If the links are clickable.
    • If the HTML code directs to the correct URL.
    • If the ID in the post’s URL matches this post’s ID from the database.
    • If the URL parameters of a link are available for manipulation only to authorized users.

    Using a white box approach, a QA specialist only tests the URL parameters and if the HTML points to the proper URL. With black box testing, the QA specialist only checks link clickability.

    Alternatives to gray box testing

    There are three approaches to software testing: black box, white box, and gray box. The main difference between these approaches is the amount of access the tester has to the internal information and source code.

    Comparison of gray box testing with alternative methods

    Comparison of gray box penetration testing with the alternative methods
    Comparison of gray box penetration testing with the alternative methods

    Compared to black box testing, the gray box approach, as well as the white box, provides a deeper understanding of an application’s underlying technology and architecture, making it easier to identify technical issues. At the same time, compared to white box testing, the gray box approach gives a more realistic view of software quality by incorporating user context into the testing process.

    Knowing the advantages and limitations of each approach helps organizations determine the most appropriate testing method for their specific needs.

    Gray box testing techniques

    Several techniques may be employed in gray box testing, depending on an organization’s objectives and the issues that the assessment is intended to address.

    Gray box penetration testing techniques
    Gray box penetration testing techniques

    Matrix testing

    This technique is applied to define the variables of a program and assess the risks they pose. Variables are used to store and label data to be referenced and manipulated within a program. Matrix testing analyzes the performance of variables and identifies the unused or inefficient ones.

    Regression testing

    Every change made to an application has the potential to lead to errors. Regression testing is used to ensure that modifying a program does not cause new bugs and does not impact the functionality of the program.

    Pattern testing

    This testing technique analyzes past errors to establish the patterns that led to their occurrence. It is used to keep a record of all such issues and their causes and to create test cases to prevent similar errors from arising in the future.

    Orthogonal array testing

    Orthogonal array testing is a statistical approach that is used when the tested software has large data inputs. It maximizes test coverage by combining inputs and testing the system with a small number of test cases. This reduces time consumption and costs associated with software testing.

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    The gray box testing process

    Automating the testing process and optimizing the necessary tools simplify the gray box testing procedure. The main steps involved in gray box testing are as follows:

    1. Selecting input. As gray box testing comprises both black and white box testing, the QA specialist chooses inputs from both of these approaches.
    2. Identifying output. The QA specialist identifies the expected outputs for the selected inputs.
    3. Identifying paths. The QA specialist sets all the key paths for the testing process.
    4. Identifying subfunctions. For deep-level testing, the QA specialist determines subfunctions (i.e., additional functions).
    5. Input for subfunction. The QA specialist selects inputs for subfunctions.
    6. Output for subfunctions. The QA specialist establishes the expected outputs for subfunctions.
    7. Test cases. The QA specialist performs test cases for subfunctions and checks the accuracy of test results.
    8. Repeat. The QA specialist carries out steps 4 to 7 for other functions and subfunctions.

    Various tools may be used in gray box testing. Among the most popular are Selenium, Appium, Postman, JUnit, NUnit, DBUnit, Cucumber, Burp Suite, RestAssured, Chrome Dev Tools.

    Gray box testing tools
    Gray box testing tools

    Advantages of gray box testing

    In software engineering, gray box testing offers a range of benefits.

    High efficiency

    The gray box approach involves the application of clear testing goals to check a specific software component. It also considers both user and developer perspectives, improving the quality and efficiency of the testing process.

    Comprehensive test coverage

    Gray box testing provides better test coverage than black or white box testing alone. It incorporates internal and external testing elements into the testing process and examines both the architecture of the application component and the application’s functionality from the end-user’s perspective.

    Risk management

    Gray box testing identifies and mitigates potential issues before they become significant problems, helping organizations enhance risk management. With access to particular system components, testers can ensure that bugs are fixed immediately after detection and subsequently check how the changes improve software performance.

    Limitations of gray box testing

    However, certain aspects of the gray box approach may have an adverse effect on the testing process:

    Limited testing depth

    Although gray box testing provides a more comprehensive view of software quality than black box testing, it may not offer the depth of white box testing, as testers do not receive full access to information about the software architecture.

    Risk of implementation errors

    Since gray box testing requires a combination of manual and automated testing techniques, there is a risk of implementation errors in the testing process.


    With organizations placing a greater emphasis on software quality, the prospects of gray box testing are promising. As technology continues to evolve, gray box penetration testing is likely to play an increasingly important role in ensuring the reliability and security of software products. Gray box testing is an effective approach to software testing that provides a balanced assessment of software quality.

    An experienced QA team can ensure that gray box testing is performed using the necessary tools and techniques. EffectiveSoft offers professional support for software testing and quality assurance to help our clients fully utilize the gray box approach. Contact us to get a project estimate.

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