Grey Box Testing Tutorial With Examples, Tools And Techniques

This tutorial is a complete guide to Grey Box Testing, its advantages, examples, and tools, etc.:

Grey box testing also spelled as Gray box testing is known as Translucent testing. It is effectively used for Web-based applications. This software testing technique is beneficial in Integration testing, Penetration testing, and Domain testing.

The major objective of this testing technique is to find issues occurred because of the incorrect internal structure or incorrect usage of the application.

Grey Box Testing

What Is Grey Box Testing

Grey box testing is a software testing technique in which testers do not have complete knowledge about the product, they have limited information for internal functionality and code. They do have information about the requirement and also have the access to detailed design documents.

This testing technique is a combination of Black box testing and White box testing.

In Black box testing, the tester does not have any knowledge about the code. They have information for what will be the output for the given input. In White box testing, the tester has complete knowledge about the code.

Grey box tester has knowledge of the code, but not completely.

Black box and whitebox


The purpose of Grey box testing is to improve the quality of the product for which it covers both functional and non-functional testing altogether, which saves time and the lengthy process to test the application.

Another purpose is to have the application tested from the user’s perspective rather than the designer’s opinion, and to get the developers enough free time to fix the bugs.


#1) While testing a website, if the tester clicks on any link and it comes up with an error, the Grey box tester can make changes in the HTML code to check the same.

In this particular scenario white box testing is being done by changing the code and as the tester is testing the changes at the front end–black box testing is also being done. Combination of the White box and Black box results in grey box testing.

#2) Grey box testers can analyze the error codes and explore the cause in detail if they have knowledge and access to the error code table in which cause is provided against the error code. Say, the webpage gets an error code as “Internal server error 500” and the cause against this error is shown as server error in the table.

Using this information, a tester can further analyze the issue and provide the details to the developer rather than just raising the issue to them.

#3) Grey box testers can analyze the log files themselves to find the root cause for the issue. The grey box tester can easily analyze low performance, crashes in the application, or other issues.

Techniques For Grey Box Testing

Let’s discuss the techniques used for Grey Box testing:

  1. Matrix testing
  2. Regression testing
  3. Orthogonal Array testing
  4. Pattern Testing

#1) Matrix Testing

Software developers provide all the variables in a program along with the technical and business risks that are linked with them. The matrix testing technique tests the risks defined by the developers.

Matrix technique states all the used variables in a program. This technique helps to identify and remove the variables which are not being used in the program and in turn, helps to increase the speed of the software.

#2) Regression Testing

Regression testing is performed when any change is done in the software or any defect is fixed. It is done to ensure that a new change or fix done has not impacted any existing functionality of the software.

#3) Orthogonal Array Testing or OAT

This testing technique is used more for complex functionalities or applications, as this technique is utilized when maximum coverage of code is required with minimum test cases and has large test data with n number of combinations.

#4) Pattern Testing

Pattern Testing is performed based on the previous defects found in the software. Defect record is analyzed for the cause of defects and test cases are created keeping the defects and their cause in knowledge to find defect before the software goes into production.

Advantages Of Gray Box Testing

These are as follows:

  • The quality of the software gets improved.
  • This technique focuses more on user perception.
  • In grey box testing developers are benefitted as they get enough time for bug fixing.
  • As grey box testing is a combination of both black box and white box, the benefits of both are acquired.
  • Grey box testers do not require having high programming knowledge for testing the product.
  • This testing technique is effective in Integration testing.
  • This testing technique helps to have no clashes between the developer and the tester.
  • Complex applications and scenarios can be tested effectively with this technique.
  • This testing technique is non-intrusive.

Disadvantages Of Gray Box Testing

These are as follows:

  • Complete white box testing cannot be performed in grey box testing, as a source cannot be accessed.
  • For a distributed system, it becomes difficult to associate defects in this testing technique.
  • Test case creation for grey box testing is complex.
  • Because of limited access, code path traversal access also gets limited.

Steps To Perform Translucent Testing

Let’s go through the steps that are performed for grey box testing.

Step 1: Select Input
White box and Black box testing inputs to be identified.

Step 2: Identify Output
Outputs to be identified for the inputs selected in step 1.

Step 3: Identify the Key Paths
All the major and key paths to be identified for the testing phase.

Step 4: Identify Subfunctions
Subfunctions to be identified to perform testing at the next level, i.e. to test more in-depth into the product.

Step 5: Identify Subfunction Input
Inputs for subfunction to be identified in this step.

Step 6: Identify Subfunction Output
Outputs to the above-selected input for subfunctions to be selected or identified.

Step 7: Execution of subfunction
Test case for subfunction to be executed.

Step 8: Verification of executed subfunction
Verification to be done for the execution done in Step 7 to identify whether the test results are as expected or not.

Step 9: Repetition of Step 4 and Step 8

Step 4 i.e. Identify Subfunction and Step 8 i.e. Verification of the executed subfunctions is to be repeated for the rest of the subfunctions.

Step 10: Repetition of Step 7 and Step 8
Execution and Verification Step to be repeated for the rest of the subfunctions.


Testing a website form wherein providing email id and submitting the form sends an email to the user for confirmation and information.

As a Black box tester – the tester will provide the input as valid/invalid email ids to check for the system behavior.

As a Grey box tester – the tester will have knowledge about the validation, such as email validation will be done using JavaScript on the client-side.

Having the above knowledge tester will add up another test case in his list that is to test the scenarios by disabling JavaScript of the browser.

Here, clearly, we can see the advantage of using Grey box testing. Additional information helped the tester to create and perform additional test cases.

Difference Between Black Box, White Box, And Grey Box Testing

Black Box TestingWhite Box TestingGrey Box Testing
Tester does not have any knowledge and information for the internal structure.The internal structure is completely known.The Internal structure is partially known.
Also known as Closed box, Functional testing, and Data-driven testingAlso known as Glass, Clear box, Structural testing, or Code-based testing.Also known as Gray box testing or translucent testing.
Done by testers, developers, and the end-users.Done by testers and developers only.Done by testers, developers, and the end-users.
Not suitable for algorithm testingSuitable for Algorithm testingNot suitable for algorithm testing
Tester has nothing to do with the internal working of the system.Tester has complete knowledge of the internal working of the system.Tester has partial knowledge of the internal working of the system
Hidden errors cannot be found easily.Hidden errors can be found very easily as internal working is well known to the tester.Not easily found but can be found at the user level.
Black box testing is the least time-consuming processWhite box testing is a time-consuming process Grey box testing takes less time than white box testing
Less exhaustive than the white box and grey box testingMost exhaustive process.Partially exhaustive process.

Tools For Grey Box Testing

These are enlisted below:

  1. Selenium
  2. Appium
  3. Postman
  4. JUnit
  5. NUnit
  6. Cucumber
  7. DBUnit
  8. Burp Suite
  9. RestAssured

Frequently Asked Questions

Q #1) What is Grey Box Testing in Software testing?

Answer: Grey box testing is performed to remove any defects because of issues in the internal structure of the application. This testing technique is a combination of Black box testing and White box testing.

Q #2) Enlist Grey box testing example.

Answer: Grey box testing includes both black box and white box testing. Tester has access to all the detailed documents and requirements. Example: In case the link of a website is not working, it can be checked and changed in HTML directly and can be verified in real-time.

Q #3) What is the advantage of Grey box testing?

Answer: Grey box testing has several advantages. Few of them are mentioned below:

  • Improves the quality of the product.
  • Complex applications can be tested with ease.
  • Do not require the tester to have complete knowledge of coding.
  • Obtain benefits of both black box and white box testing.

Q #4) What does Gray box testing mean?

Answer: Grey box testing is defined for the applications where the internal working of the application is not known completely. It is best for web-based applications. For functional and domain testing, it is considered the best approach. This testing is focused more on user perspective than designing.

Q #5) Who does Grey box testing?

Answer: It is done by the testers themselves. It is done when testers do not have complete information about the internal structure and working of an application. In this testing, the input is provided on the front end and output is verified at the back end.


Gray box testing is very beneficial as it combines both the testing techniques i.e. black-box testing and white box testing. This testing technique is more effective for web-based applications, functional and domain testing. Test case creation for grey box testing includes all the aspects such as security, database, browser, GUI, etc.

This testing technique handles complex scenarios more perceptively than other techniques. It is based on functional specifications and not on source code or binaries.