Did you know all software developers have a common goal? They have an utmost dream to develop a usable, secure, and performant application. And, you need to test your application thoroughly to fulfill the goal.

Testing is a crucial aspect of building a robust application. It ensures the app meets the expected quality. That’s why we will examine one of today’s most vital testing methods. Today we’ll talk about white box testing.

The white box testing method analyzes the internal structures, internal design, used data structure, working of the software, and code structure. Let’s figure out the techniques, tools, pros, and cons of using white box testing.

What is White Box Testing?

It is a vital software testing technique. Developers use this to verify the input-output flow and enhance usability, security, and design. Code is visible to testers in white box testing.

Therefore, another name of this testing method is Clear box testing. You can also call it Glass box testing, Code-base testing, Transparent box testing, or Open-box testing.

Developers use two parts of box testing approaches for testing applications. The counterpart of white-box testing is black-box testing. Black box testing involves an end-user-type perspective. But, white box testing looks after the inner functions of a software. So, it is all about internal testing.

How is White Box Testing done?

Let us make it simple for you. You can divide the process of white box testing into two steps. This is what the developers do when they test an application.

Step – 1. Understand the source code

A tester needs to learn and understand the app’s source code at first. White box testing involves the inner functions of an app. So, the tester must have sound knowledge of the programming languages that the developers have used to write the app.

The tester should be aware of source coding practice. Ensuring security is the primary objective of white box testing. The tester has to find out the security-related issues of the software and prevent attacks from hackers.

Step – 2. Create test cases

The second step of white-box testing is verifying the application’s source codes for proper structure and flow. They usually write more code to test the source code of the software. The testers develop small tests for every series or process in the application.

This method demands intimate knowledge from the tester. It also includes manual testing, trial, and error testing.

Types of White Box Testing

types of white box testing

There are several testing types in white box testing. Testers use those types of testing to evaluate the usability of an app. It also helps them check the block of code or a particular software package. Have a look at the list of the types of Clear box testing.

Unit Testing

Unit testing is the first type of testing that a tester applies to an app. They use it on every block or unit of code.

The developers complete that unit testing part essentially. A software developer creates a few lines of code, an object, or a single function before starting the unit test. It helps them to identify the bugs. Identifying bugs in the early stage of app development reduces the expense and makes it easier to fix.

Testing for Memory Leaks

Memory leaks can cause slower running apps. All you need here is a QA expert who has experience detecting memory leaks. They can quickly identify the slow-running software.

White Box Penetration Testing

The developer carries complete information about the application’s source code when doing this testing. They also have detailed information regarding IP address, network, and server. The testing aims to attack the code from different angles to expose security threats.

White Box Mutation Testing

Developers often use mutation testing to find out several coding techniques. That’s how they discover which method is best to use to expand a software solution.

White Box Testing Techniques

Code coverage analysis is the most vital white box testing technique. It removes gaps in a test case suite. This method helps us identify the programming areas we have not examined by a set of test cases.

The tester can quickly identify the gaps this way. Then, they develop test cases to examine untested areas of the code. That’s how we can easily enhance the quality of the software product.

You can avail a bunch of automated tools to perform code coverage analysis. We have listed down the vital coverage analysis techniques here. Check it out!

Statement coverage

Statement coverage includes every possible statement in the code. In this technique, the tester tests every statement at least once.

Statement coverage Example

Look at the flowchart once. You will see every node is traversed at least once. The technique covers all lines of the code. So, it is easy to point out the incorrect codes.

Branch coverage

Branch coverage tests all the possible paths of a software application. It checks every conditional loop of the development as well. In this technique, the developers design the test cases to traverse every branch at least once.

Branch coverage example

Image 2: Branch Coverage example that shows all edges of the flowchart are covered.

Branch Coverage helps you to attain 80-90% code coverage.  It is sufficient to get bug-free software.

Condition Coverage:

This technique covers all individual conditions. Have a look at the following example:


IF (X ==0 | | Y ==0)


In this example, you can see 2 conditions such as X == 0 and Y == 0.

If you test these conditions, you will get TRUE and FALSE as their values. Here is a possible example:

#TC1 – X=0, Y=55

#TC2 – X=5, Y=0

Along with these, there are many coverage types like Path Coverage, Function Coverage, Condition Coverage, Multiple Condition Coverage, etc. all the techniques have specific merits and attempt to cover each area of software code.

Pros and Cons of Using White Box Testing

Here are the merits and demerits of white box testing.


  • Easy to automate
  • White box testing is a very thorough technique method
  • All the code structures are thoroughly tested
  • It helps the testers to optimize the code and remove error from it
  • White box testing helps to remove extra lines of code
  • This testing method can start earlier as it doesn’t need any interface.


  • It is a complex testing method
  • Sometimes white box testing is not  realistic
  • All the existing codes are tested. So, it is tough to detect missing functionalities
  • Testers need to have in-depth knowledge of the code and the programming language
  • Rewriting and redesigning of code demand test cases to be written again
  • It is costly

Related:- Unit Testing vs Functional Testing

White Box Testing FAQs

white box testing FAQs
White Box Testing FAQs

What is white box testing?

Ans; Testers use this software testing method to test the business logic and structure. It has several other names, such as open box testing, glass box testing, structural testing, logic-driven testing, path-driven testing, and so on.

What is white box used for?

Ans: It is a technique of software testing. The developers use the method to test the internal structures and workings of the applications.

Who uses white box testing?

The developers can perform white box testing. Specifically, the testers use this method to test the programs.

Related:- What is functional testing

Ending note:

You already know that white box techniques let the developers evaluate the code and the internal structure of the software. Sometimes, it can be complex and more expensive compared to black-box testing.

The developers also need to be knowledgeable and experienced.

Still, when you are working in the software industry, this testing method will help you improve your knowledge and skills.

And, the complexity of the testing method has a lot to do while you test the application. The complexity of white box testing makes it equally effective for testing both small and large applications. You can test a small application that performs a single operation in a few minutes. And, a large one might take weeks.

About Samriddhi

Samriddhi is a storyteller and content marketing professional at Invedus. She writes engaging and data-driven content on outsourcing trends and technology strategies. She has skills in content writing, social media marketing, graphic design, and business analysis. She loves to visit scenic tea shops in the green hill stations.