What is a Grey Box Testing?

Greybox testing (GBT) is a software testing method that includes judging a software program based on a limited understanding of its core functions. It is a combination of the two since it offers access to internal coding to construct test cases as white box testing and testing techniques are performed at the functionality level as black-box testing.

GreyBox testing (GBT) is a popular method for identifying contextspecific issues in online applications. For example, if a tester finds a fault during testing, he fixes the code and retests it in real time. In order to improve testing coverage, it focuses on all layers of any difficult software system. It allows both the display layer and the core code structure to be tested. It's commonly used in penetration and integration testing.

Gray Box Testing (GBT) is a software testing method that combines White Box Testing (WBT) and Black Box Testing (BBT) (BBT).

  • White Box testing is used to examine the internal structure of a product.

  • The inner workings of Black Box Testing (BBT) are a mystery.

  • Grey Box Testing's (GBT) fundamental structure is only partially understood.

Gray Box Testing (GBT) in Software Engineering allows you to test both the display layer and the core component of an application. It's mostly used for Integration and Penetration Testing.

Gray Box Testing Example: While the testing website features such as links or orphan links, if the tester discovers any problems with these links, he may make modifications to the HTML code right away and test in real-time.


#1) If a tester clicks on a link and encounters an error while testing a website, the Grey box tester can make changes to the HTML code to validate the problem.

In this case, white box testing is performed by modifying the code, and black-box testing is performed concurrently as the tester tests the changes at the front end. Grey box testing is produced by combining the White box with the Black box.

#2) Grey box testers with knowledge of and access to the error code database, which includes the cause for each error code, may analyze error codes and explore the cause in more depth. Assume the webpage receives an error code of "Internal server error 500," and the reason for this issue is listed in the table as a server error.

Using this information, a tester may further investigate the problem and offer specifics to the developer rather than simply reporting it to them.

#3) Grey box testers can examine the log files to determine the root cause of the problem. The grey box tester can simply examine low performance, program crashes, and other problems.

What is the purpose of GreyBox testing?

The following are the reasons for GreyBox testing −

  • It combines the advantages of both Blackbox and WhiteBox testing.

  • It incorporates both developers' and testers' input values at the same time in order to improve the overall quality of the product.

  • It shortens the time required for the lengthy process of functional and non-functional testing.

  • It offers the developer enough time to remedy any product flaws.

  • It incorporates the user's point of view rather than the designer's or tester's.

  • It entails a thorough evaluation of requirements and specification determination from the user's point of view.

Strategy for Gray Box Testing

It is not required for the tester to have access to the source code in order to do Gray box testing. A test is created using information about algorithms, architectures, internal states, and other high-level descriptions of program behavior.

  • Gray box testing can be done in a variety of ways.

  • It employs a basic black box testing approach.

  • It is based on the development of required test cases, and as a result, it establishes all of the criteria before the program is tested using the assertion technique.

Grey box testing techniques

Matrix Testing

Grey Box testing is the term for this type of testing. It lists all of the variables that are utilized in a program. Variables are the components in every program that allows values to move through it. It should be tailored to the requirements; otherwise, the program's readability and speed would suffer. The matrix approach is a method for removing unneeded and uninitialized variables from a program by detecting utilized variables.

Regression Testing

Regression testing is used to ensure that a change to one area of software does not have an unexpected or undesirable effect on another section of the product. Any defects discovered during confirmation testing were corrected, and that portion of the program began to function as planned; nevertheless, it is possible that the fixed flaw caused a new problem elsewhere in the software. Regression testing addresses these types of problems by employing testing techniques such as retesting hazardous use cases, retesting behind a firewall, retesting everything, and so on.

Orthogonal Array Testing or OAT

The goal of this testing is to cover as much code as possible with as few test cases as possible. The test cases are written in such a manner that they cover the most code as well as the most GUI functionalities with the fewest amount of test cases.

Pattern Testing

Pattern testing applies to software that is created by following the same pattern as prior software. The same kind of flaws is possible in this form of software. Pattern testing identifies the causes of failure so that they may be addressed in future software.

Greybox approach often uses automated software testing tools to carry out the testing procedure. Stubs and module drivers are supplied to a tester to alleviate the need for manual code development.

The following are the steps to do Grey box testing −

Step 1 − Make a list of all the inputs.

Step 2 − Determine the outcomes

Step 3 − Make a list of the key routes.

Step 4 − Determine the Subfunctions

Step 5 − Create subfunction inputs.

Step 6 − Develop Subfunction Outputs

Step 7 − Run the Subfunctions test case.

Step 8 − Check that the Subfunctions result is valid.

Step 9 − Repeat steps 4-8 for each additional Subfunction.

Step 10 − Carry on with steps 7 and 8 for the remaining Subfunctions.

GUI-related, security related, database related, browser related, operational system related, and so on are examples of test cases for grey box testing.

Gray Box Testing's Benefits

The following are some of them −

  • The software's quality is improving.

  • This method focuses on the user's perception.

  • Developers gain from grey box testing since they have more time to resolve bugs.

  • Grey box testing combines both black box and white box testing, giving you the best of both worlds.

  • Grey box testers don't need to have extensive programming expertise in order to evaluate a product.

  • Integration testing benefits from this testing method.

  • This testing approach ensures that the developer and the tester are on the same page.

  • This approach may be used to test complex apps and situations.

  • This kind of testing is non-intrusive.

Gray Box Testing's Drawbacks

  • Grey box testing does not allow for complete white box testing because a source cannot be accessed.

  • This testing approach makes it harder to link problems in a distributed system.

  • It is difficult to create test cases for grey box testing.

  • Access to code path traversal is likewise restricted as a result of limited access.

Gray Box Testing Difficulties

  • When a component under test fails in some way, the continuing operation may be terminated.

  • When a test runs completely but the substance of the result is wrong.


Grey box testing can minimize the overall cost of system faults and prevent them from spreading further.

Grey box testing is best suited for GUI, Functional Testing, security assessment, online applications, web services, and other similar applications.

  • Grey box Testing Methodologies

  • Matrix Testing

  • Regression Testing

  • OAT or Orthogonal Array Testing

  • Pattern Testing

Frequently Asked Questions

Q #1) In software testing, what is grey box testing?

Answer − Grey box testing is used to eliminate any faults caused by difficulties with the application's internal structure. This testing method combines Black box and White box testing techniques.

Q #2) Provide an example of grey-box testing.

Answer − Both black box and white box testing are included in grey box testing. All of the specific documentation and requirements are available to the tester. For example, if a website's link isn't working, it may be examined and updated immediately in HTML and confirmed in real time.

Updated on: 02-Dec-2021


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