What is White Box Testing?

By | May 20, 2020
White Box Testing

What is White Box Testing?

This software testing is used for testing the internal structure, coding and design of the software. The primary focus of White Box Testing is to verify input and output flow through the application so that developers can improve usability, design and strengthen security. Therefore all codes are visible to a tester in this software testing. There are various names of White Box Testing such as clear Box Testing, structural testing, open Box Testing, transparent Box Testing, Glass Box Testing and code-based testing. It is a subpart of complete testing because the testing involves two ends, White Box Testing and Black-Box Testing. Black Box Testing includes testing from the end-user type perspective. On the other side, White Box Testing is entirely based on the internal operations of an application. The title White box is used due to its see-through box concept. The clear box/ White box name signifies the capacity to see through the software’s external casing into its internal workings. Furthermore, the “Black box” in the “Black Box Testing” signifies not being capable of seeing the internal workings of the software so that the end-user experience can be tested.

Factors that can be verified White Box Testing

It includes the testing of all software code for the following aspects:

  • Inner security holes
  • Broken or inadequately structured paths in a coding method
  • The flow of particular inputs by the code
  • Expected output
  • The functionality of a restricted loop
  • Testing of every statement, function, and object on a specific basis

Software testing can be performed at a system, unit level and integration of software development. According to the objectives of White Box Testing, we can verify a workflow of any application. This software testing includes a predefined series of inputs for comparing with expected outputs, so in case of input does not match with the expected output, then testers can eliminate the error from the application.

The process to perform White Box Testing:

We have divided the process into two basic parts so that you can understand the process briefly. So let’s discuss the process of testing an application through the technique of White Box Testing:

Step 1: Understanding the Source codes

Firstly, a tester/developer requires understanding and learning the source code of any application.

As we know that White Box Testing includes internal workings of an application, so the tester must be proficient in the programming languages. These languages are used in the testing of various applications. Apart from it, the tester must be highly aware of secure coding methods, and security is a primary objective of testing software. Hence, it is also essential that a tester must be capable of finding security issues and preventing attacks from hackers and who may insert malicious code in the application both knowingly or unknowingly.

Step 2: Creating a test case and execution

The second essential step to White Box Testing includes testing the source code application for appropriate structure and flow. Testers need to create more and more sources for testing the application and develop little tests for every process in an application. This process demands specialized knowledge of the code. Other processes involve Manual Testing, error testing and the usage of testing tools, so we will discuss these aspects in further information.

Techniques of White Box Testing

The primary technique of White Box Testing is Code Coverage analysis that reduces gaps in the test case suite. It recognizes areas of programs that are not operated by any set of test cases. After the successful identification of gaps, the tester creates a complete test case for verifying untested aspects of code so that the quality of the product/software can be increased. There are various automated test tools available for performing code coverage analysis. So let’s discuss a few techniques of coverage analysis in brief:

1. Statement Coverage

This technique needs all probable statements in the code, which is required to be tested through the testing method of software engineering.

2. Branch Coverage

Branch coverage technique checks all possible ways of the software application. , there is various coverage types like:

  • Condition Coverage
  • Multiple Condition Coverage
  • Path Coverage
  • Function Coverage

Every technique consists of values and attempts for testing all parts of the software code. Testers can usually achieve 80 to 90% code coverage through Statement and Branch coverage.

Types of White Box Testing

It includes several testing types which are used for evaluating the usability of any application, a block of code or particular software package. So here is the list of various types of testing:

1. Unit Testing

It is the most common and type of White Box Testing done on the application. Unit Testing is done on each unit/ block of code after it is developed. Unit testing is mostly performed by the programmer. As per the perspective of a software developer, you need to produce a few code lines. Then test these codes to make sure that codes are working before continuing Unit Testing. It helps to recognize a majority of errors in the early lifecycle of software development. Therefore bugs and errors can be identified by a smooth and cheaper way.

3. Memory Leaks testing

Memory leaks always lead to slower running applications. A quality developer must be a specialist in detecting leaks because it is essential to run software appropriately.

Apart from it, there are various testing types which can work in both White box and black-Box Testing.

4. White Box Penetration Testing

In this type of testing, the tester has full information of the application’s comprehensive network, source code, IP addresses and server. The primary aim of this testing is to penetrate or attack the codes from various angles for exposing security threats and find errors in it.

5. White Box Mutation Testing

This type of testing is used for discovering the most suitable coding techniques so that testers can expand a software solution.

Various types of Tools

There are various types of tools available, so here is the list of some tools:

Pros and Cons


  • This testing helps to optimize the codes by finding hidden bugs and errors from the software.
  • Test cases in White Box Testing can be efficiently automated.
  • Testing is more accurate due to all code paths typically covered.
  • If GUI is not available, then testers can start the testing in SDLC.


  • Usually, It can be complicated and expensive.
  • Production errors occur if one developer executes the test case, and another developer doesn’t execute the test case properly.
  • It needs all professional resources, with complete knowledge of implementation and programming.
  • It is a little bit time-consuming, larger programming applications take more.


It is a bit complicated, and the complexity includes a lot of work for testing the application appropriately. In this article, we have discussed White Box Testing completely regarding the overview, process, types and tools so that you can understand every aspect of this testing.

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