What is Glass Box Testing?

Introduction of new and better technology and techniques has made software testing hassle free and convenient. Software testers around the world are adopting these new innovations and are effectively improving the quality, performance, functionality, and other components and features of the software. Glass Box Testing is one such software testing technique, which has gained immense popularity among software engineers around the world. Therefore, to help you understand this type of software testing methodology, here is an elaborative discussion on the same.

What is Glass Box Testing?

A method of testing, glass box testing is also referred as clear box testing, open box testing, logic driven testing, path driven, testing or structural testing and is mainly used by software testers to examine the structure of the program.

White Box Testing, Glass Box Testing, transparent box testing or clear box testing offers an insight into the program code of the software and derives test data from the same program code or logic. The main objective of this type of testing is to use the internal knowledge of the software to guide the selection of the test data and to improve the test design.

Glass Box Testing methodology is one of the best testing methodology, as it overcomes the numerous limitations of both black box testing as well as white box testing. Moreover, it uses internal information, which is gathered from various sources, like design techniques, code, etc., to augment black box testing.

Glass Box Testing Techniques:

Glass box testing is an extremely important type of software testing methodology, wherein testers cannot create test cases until the code of the program is written completely. Additionally, with the assistance of this technique, software testers can improve the effectivity and accuracy of the software product.

  1. Statement Coverage: This type of glass box testing technique is mainly focused in ensuring that all the statements in the program are tested thoroughly and are offering accurate and expected result. This result is achieved with the assistance of a basic formula, which is mentioned below: Statement Coverage Formula =(Number of Statements Exercised/Total Number of Statements) x 100.
  2. Path Coverage: Another beneficial glass box testing technique, path coverage is used to test all the paths that are included in the program. With the assistance of this technique, testers are able to validate that all the statements in the program are covered as well as tested. This is ensured with the help of path coverage formula that is mentioned below:
  3. Path Coverage Formula= (Number of path exercised/ total number of paths in the program) x100.
  4. Branch Coverage: Branch coverage is another important glass box testing technique, wherein a series of test are executed to ensure that all branches in the program are tested at once. Similar to other technique, branch coverage also uses a formula to validate the coverage of all branches. This formula is:
  5. Branch Coverage Formula = (Number of decision outcomes tested/Total number of decision outcomes) x 100.
glass box testing Infographics

Advantages of Glass Box Testing:

Software testing techniques or methodologies offer testers numerous benefits. From improving the product’s basic functionality to its major features, through testing a tester can validate uncountable elements and components of the software. Likewise, glass box testing also imparts various benefits to testers, some of which are mentioned below:

  • Here, testing is executed from the point of view of the source code.
  • This testing can be easily automated.
  • Glass box testing is more thorough as it tests all the paths and branches included in the program.
  • It helps reveal errors hidden in the code.
  • Can effortlessly spot issues and dead codes in the software program.
  • Improves the accuracy, coverage, performance, & other features of the software.
  • Can scan the internal actions & structure of the application.

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Disadvantages of Glass Box Testing:

After understanding the various advantages of glass box testing it is vital for testers to be aware of it drawbacks or disadvantages, which can impact the performance, quality, or any other important feature of the software. Hence, here are few disadvantages of glass box testing, which will help testers make informed decision.

  • In-depth knowledge of the program is required, which makes testing complicated.
  • Team needs to be adept in programming language, which brings complexity into the testing.
  • It cannot detect the missing functionality of the software.
  • Knowledge of the code is necessary to derive test cases from them.
  • Test cases cannot be created until the programme code is written.
  • Glass box testing is expensive as it requires ample time and money for test execution.

Difference between Glass Box Testing and White Box Testing:

Glass box testing and white box testing are two types of software testing methodologies, which are usually confused by people across the world. Though, both of them test the internal structure of the program, their objective testing is different from each other. Therefore, to avoid such a confusion among these two types of software testing techniques, here is a comparison of the two.

  • Aim: As stated above, glass box testing examines the program structure and derives the test data from the program logic or code. Whereas, in white box testing software’s internal coding and structure is tested to validate and strengthen the security, the flow of inputs and outputs through the software, as well as to improve the design of the usability and design of the program.
  • Techniques: Glass box testing uses statement, branch, & path coverage to validate the accuracy of the source code. On the other hand, the white box testing uses statement, branch, path, condition, multiple condition, function coverage etc to test the software program.
  • Advantages: White box can be commenced during the early stages of Software Testing Life Cycle(STLC) and is more thorough as it covers more paths of the program, while glass box testing overcomes the limitations of both black box and white box testing and offer various advantages mentioned above.


Software testing is an integral part of software development life cycle (SDLC) and without it delivering a quality and defect-less software is impossible. Similarly, glass box testing is a software testing technique, used by testers to validate the quality of the internal structure of the software. This testing methodology is extremely beneficial and helps testers overcome various limitations of black box and white box testing.

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