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White Box Testing


Professionalqa white box testing image

Based on different needs and requirements, a software testing may be carried out using various approaches such as manually or using automation tool, executing or without executing the code. Similarly, a software application may also be tested externally and internally using Black-box and White-box testing methodologies respectively.

Let's get started with White Box Testing.

What is white box testing?

White Box term is referred to a transparent or glass box through which elements could be seen i.e. through transparent or glass edges, internal structure of the box may be explored to study, analyse and evaluate the internal working of the application.

white box


White box testing is the testing of the internal structure of an application product through the derivation of test data from the program logic. It is also known by other names such as Open box testing, structural testing, logic driven testing and clear box testing.

White box testing counterpart: black box testing does not involve the testing of the internal structure and framework of the application rather it evaluates the quality of the system externally from the end-user's perspective.

Refer to our article White Box Testing Vs Black Box Testing to gain and understand exact points of differences white box and black box approach of testing.

What all is tested under white box testing?

White box testing is employed to check the following aspects

  1. Checking for loopholes in internal security features.
  2. Detecting poorly structured paths in coded structures.
  3. Proper functioning of conditional loops.
  4. The smooth flow of input data through the code.
  5. Individual testing of every object or functionality related to the product under test.

Techniques of White box testing:

  1. Statement Coverage: A code of instructions remains a statement until it gets compiled for errors and becomes part of the code structure. Under statement coverage technique of White box testing, each and every statement which is part of the code structure gets verified at least once.
  2. Branch coverage: This technique checks every single entity having a conditional loop around a decision point such as If-Then-Else statements.
  3. Path coverage: A technique more powerful than both statement & branch coverage, path coverage as the name suggests verifies every single path of an application at least once.

white box testing techniques


Read more about these white box testing approaches in our related article Statement, Branch and Path Coverage Testing.

How to go about White box testing?

white box testing working


  • Making use of the biggest advantage of white box testing, the tester should have an in depth knowledge of the source code.
  • He should make himself well versed with the programming language used as well as the intricate tools and subtle nuances involved in the development of the software product being tested.
  • Creation of tests cases for each step, path or branch of instruction either individually or in combinatorial form.
  • The test cases are then executed via hit and trial methods, manual testing or automation.
  • A final summary is generated noting down all the preparation details and the results achieved.

Benefits of White box testing

  • While box testing has edge over black box testing in revelation of hidden errors in the code.
  • White box testing is fairly easy to automate, allowing reduction in testing time.
  • Spotting of dead codes in accordance with prevalent testing practices.
  • White box testing enables easy traceability of the tests right up to the source level. This way any future changes in software to be congruently captured for changes in the tests.

Demerits of White box testing

  • Not possible to cover every possible condition for testing.
  • Since this testing approach requires a thorough understanding of the software, the testing effort requires the services of a tester having ace programming skills.
In nutshell, it may be inferred that the use of white box testing approach for the early identification of faults in code or in detecting dead code(s) not only ensures the higher quality & lesser complexity of the code but also minimizes the probability of occurrence of any unexpected issue or defect at a later stage in future.