What is White Box Testing? Techniques, Example, Types & Tools

Testing in a White Box

White Box Testing is a software examining technique that involves testing the product's underlying structure, design, and coding in order to verify input-output flow and improve design, usability, and security. White box testing is also known as Clear box testing, Open box testing, transparent box testing, Code-based testing, and Glass box testing since the code is visible to the testers.

It's one of two components of the software testing approach known as Box Testing. Blackbox testing, on the other hand, entails testing from an external or end-user perspective. White box testing, on the other hand, is focused on the inner workings of an application and revolves around internal testing.

Because of the see-through box concept, the term "WhiteBox" was coined. The name "clear box" or "WhiteBox" refers to the ability to see into the software's inner workings through its exterior shell (or "box"). Similarly, the "black box" in "Black Box Testing" denotes the inability to observe the software's inner workings, allowing only the end-user experience to be assessed.

In White Box Testing, what do you check?

White box testing entails putting the software code to the test for the following −

  • Internal flaws in security

  • Paths in the coding process that are broken or poorly structured

  • The path is taken by specified inputs through the program.

  • Expected results

  • Conditional loops are useful in a variety of situations.

  • Individualized testing of each statement, object, and function

Software development might include testing at the system, integration, and unit levels. One of the primary aims of white-box testing is to ensure that an application's operating flow is correct. It entails comparing a set of predetermined inputs to expected or desired outputs, with the goal of identifying bugs when one of the inputs fails to provide the expected outcome.

How do you go about conducting White Box Testing?

We've broken down white box testing into two simple phases to make it easier to understand. When utilizing the white box testing technique to test an application, testers do the following −

Step 1: Comprehend the Source Code

The source code of the program is generally the first thing a tester learns and understands. Because white box testing entails testing an application's inner workings, the tester must be well-versed in the programming languages used in the applications under test. Furthermore, the tester must be well-versed in secure coding techniques.

One of the main goals of software testing is to ensure that it is secure. The tester should be able to detect security flaws and prevent assaults from hackers and naive users who may purposefully or unknowingly inject dangerous code into the program.

Step 2: Create and Execute Test Case

The application's source code is tested for correct flow and structure in the second fundamental step of white box testing. One method is to write more code to test the source code of the application. For each step or sequence of processes in the application, the tester will create little tests. This method necessitates the tester's extensive understanding of the code and is frequently carried out by the developer. Manual testing, trial, and error testing, and the usage of testing tools are some of the other methods that will be discussed later in this article.

Example of White Box Testing

Code −

Printme (int a, int b) {------------ it is a function
   int result = a+ b;
   If (result > 0)
      Print ("Positive", result)
      Print ("Negative", result)
} ----------- End of the code

WhiteBox testing in software engineering aims to make sure that all decision branches, loops, and statements in the code are correct.

WhiteBox test cases would be used to put the statements in the preceding white box testing example to the test.

A = 1; B = 1

A = -1, B = -3

Techniques for White Box Testing

Code Coverage Analysis is a popular White box testing technique. A Test Case suite's holes are filled through Code Coverage analysis. It identifies parts of a program that aren't put to the test in a collection of test cases. You write test cases to check untested areas of the code once the holes have been detected, thereby improving the quality of the software product.

Code coverage analysis can be performed using automated technologies. A box tester can employ the following coverage analysis techniques −

  • Statement Coverage − During the software engineering testing process, this technique mandates that every possible statement in the code be tested at least once.

  • Branch Coverage − This technique examines every conceivable path of a software application (if-else and other conditional loops).

Aside from the aforementioned coverage kinds, there is a slew of others, including Condition Coverage, Multiple Condition Coverage, Path Coverage, and Function Coverage. Each method has its own set of advantages and aims to test (cover) all aspects of software code. You can typically achieve 80-90 percent code coverage using Statement and Branch coverage, which is sufficient.

Following are some of the important WhiteBox Testing Techniquess −

  • Statement Coverage
  • Decision Coverage
  • Branch Coverage
  • Condition Coverage
  • Multiple Condition Coverage
  • Finite State Machine Coverage
  • Path Coverage
  • Control flow testing
  • Data flow testing

Why do we do WBT?

To make certain −

  • That each module's independent pathways have been tested at least once.

  • All logical decisions were tested to see if they were true or untrue.

  • Internal data structures validity is ensured by all loops that are executed at their boundaries and within their operational constraints.

To find the types of bugs listed below −

  • When we create and implement functions, conditions, or controls that are not part of the program, we are more likely to make logical errors.

  • Design flaws resulting from a mismatch between the program's logical flow and its actual execution

  • Checking for grammatical and syntactic mistakes

White Box Testing Types

White box testing refers to a variety of testing methods that are used to assess the usability of an application, a piece of code, or a specific software package. The following is a list −

  • Unit testing − Unit testing is frequently the first type of application testing performed. As each unit or block of code is developed, it is subjected to unit testing. The programmer is primarily responsible for unit testing. As a software developer, you write a few lines of code, a single function, or an object, then test it to ensure it works before moving on to the next step. Early in the software development lifecycle, unit testing helps in the detection of the majority of issues. Bugs discovered at this stage are less expensive and easier to fix.

  • Testing for Memory Leaks − Memory leaks are one of the most common reasons for slow-running apps. When you have a slow-running software application, you need a QA professional who is skilled in detecting memory leaks. Apart from the aforementioned, both black box and white box testing include a few forms of testing. Below is a list of them.

  • White Box Penetration Testing − In this type of testing, the tester/developer has access to the entire source code of the program, as well as extensive network information, IP addresses involved, and all server information. The goal is to attack the code from several aspects in order to expose security flaws.

  • White Box Mutation Testing − White box mutation testing is frequently used to determine the optimum coding strategies for growing a software solution.

The Benefits of White Box Testing

  • Code optimization through the detection of hidden defects.

  • Cases for white-box tests are simple to automate.

  • Because all code paths are usually covered, testing is more thorough.

  • Even if a GUI is not accessible, testing can begin early in the SDLC.

WhiteBox Testing's Disadvantages

  • White box testing can be time-consuming and costly.

  • It irritates developers who are used to running white box test scenarios. Developers' lack of detail in white box testing can lead to production problems.

  • Professional resources with a thorough understanding of programming and implementation are required for white box testing.

  • White-box testing takes time, and larger programming applications require more time to thoroughly test.


White box testing is a difficult task. The application being tested has a lot to do with the difficulty involved. White box testing a small application that performs a single simple task can take minutes, whereas larger programming programs might take days, weeks, or even months to completely test.

Software testing should be performed on a software application when it is being developed, after it has been written, and again after each modification.