Home » Software Testing » What is Grey Box Testing? Types and Techniques

What is Grey Box Testing? Types and Techniques

Grey box testing or gray box testing is the software testing type, combining white box testing and black-box testing. It tests an application or software product to find defects with internal partial knowledge. However, this testing detects bugs and defects in the application occurring due to improper application’s use and code structure.

In black-box testing, testers are entirely unaware of the application’s or software product’s internal structure. On the other hand, testers know everything about the application’s internal structure in the white-box testing. However, grey box testing is the combination of both; testers are aware of the application’s partial internal structure. Here, testers can access the information about algorithms and data structures used inside the software product.

What Is Grey Box Testing?

This testing is semitransparent testing that tests any software product to identify errors and defects caused due to improper usage of applications and improper structure of code. Moreover, this testing involves debugging the software by providing input via the front-end and checking the data via the back-end. It also detects context-specific bugs that are mostly associated with web systems.

This testing type is generally useful in testing web applications. It concentrates on testing the software product’s internal working and front-end functionalities. In other terms, it focuses on the application’s code part and presentation layer.

Gray Box Testing Example

When testers test websites that contain links, if an error occurred while hitting any link in the website, they can change the HTML code and check it in real-time.

Reasons and Techniques Of Gray Box Testing

Below are some significant reasons to perform grey box testing:

  • This testing is a combination of the benefits of black and white box testing.
  • It improves the application’s overall performance and quality by combining the tester’s and developer’s inputs.
  • Developers get sufficient time to overcome and fix bugs and errors in the application.
  • This testing helps to reduce the long processes of functional and non-functional testings.
  • Testers carry out this testing process from the user’s perspective rather than the developer’s point of view.


There four different types of gray box testing – Matrix, Regression, Orthogonal Array, and Pattern. Let us discuss each testing type in detail below:

Matrix Testing

The matrix testing technique examines all technical business risks in the software product. Developers are responsible for defining all these risks. Moreover, they state all variables that are present in the application’s program. Each variable has its own business and technical risks. The matrix testing identifies all used variables in the program and removes all uninitialized and unused variables.

Regression Testing

Testers perform regression testing on the software product if there is any change made in its functionality. They achieve this testing to make sure that any changes to the software do not affect existing functionalities. Moreover, regression testing also ensures that fixing any bug does not affect the system’s existing functionality.

Orthogonal Array Testing (OAT)

Generally, Orthogonal Array Testing (OAT) is a kind of black-box testing. When the software requires maximum coverage with extremely few test cases for more extensive data, testers perform orthogonal array testing. In OAT, the test data consists of n number of combinations and permutations. Moreover, OAT is suitable for testing more complex software.

Pattern Testing

Pattern testing is suitable for applications that are developed using the pattern of preceding software. To execute pattern testing for a particular software, testers first analyze previous bugs and errors. They observe code and determine the cause of bugs. Therefore, this testing helps to design further test cases to prevent previous failure.

Steps For Performing Gray Box Testing

It is not always necessary for testers to know the system’s source code to achieve grey box testing. However, they design the test depending upon an algorithm, internal states, architecture, and the code’s behaviour. For function testing of the system, testers also use a simple black-box testing technique. Below are detailed steps involved in gray box testing:

  • Firstly, identify and choose inputs from white-box and black-box testing.
  • After choosing inputs, determine the respective outputs.
  • To traverse during the testing period, find out all significant paths.
  • Next, identify the sub-functions of the main functions for performing intense and deep testing.
  • After identifying sub-functions, determine inputs to them.
  • Identify the expected output for the input of each sub-function.
  • Perform the test case on sub-functions and verify whether the expected outcome matches the resulting outcome.

Test cases for grey box testing are related to the system’s GUI, security, database, etc.

Advantages and Disadvantages Of Grey Box Testing


  • There is no need for testers to possess high programming skills for executing grey box testing.
  • Testers and developers know the precise goal of performing testing. Moreover, this testing follows the users perspective.
  • With grey box testing, the system’s or software product’s quality gets improved.
  • As this software testing type is unbiased, there are no conflicts and arguments between developers and testers.
  • Gray box testing is effective in integration testing and is non-intrusive.


  • If distributed systems undergo grey box testing, it becomes difficult to associate defects found.
  • The majority of test cases in this testing are challenging to develop. It is not suitable for algorithm testing.
  • The system’s source code is not accessible. As a result, white-box testing is not possible using this testing.


Testers may face gray box testing challenging when:

  • The test executes completely, but the result generated is not correct.
  • Any component undergoing the test encounters some failure; it may result in the abortion of the current operation.


Gray box testing is best applicable for web applications. They have distributed systems or network. Hence, white-box testing for web applications is not suitable due to the absence of source code. Moreover, black-box testing is also not possible for web applications due to a contract between developer and consumer. Therefore, gray box testing is more effective, as sufficient data is available in Web Services Description Language.

This type of testing is also best applicable for business or functional domain testing. Due to the functional testing’s characteristics, grey box testing is applicable for it. Functional testing helps testers to determine whether the software meets the pre-defined requirements.

Do You Know?
1. What is Regression Testing?
2. What is White Box testing?
3. What is black box testing?
4. What is Exploratory Testing?
5. What is Functional testing?
6. What is ETL Testing?
7. What is API Testing?
8. What Is Grey Box Testing?

Pin It on Pinterest