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Table of contents
Techniques for White Box Testing
Statement Coverage
Branch Coverage
Path Coverage
White Box Testing Tools
Advantages and disadvantages of White Box Testing
Advantages of White Box Testing
Disadvantages of White Box Testing
Difference between White Box Testing and Black Box testing
Key Takeaways
Last Updated: Mar 27, 2024

White-Box Testing

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White Box Testing is a type of testing in which the tester has a deep understanding of the system's inner workings or components under test, which Black Box Testing does not provide.

You should follow the below steps for doing the testing: 

  1. Design all test scenarios, test cases and prioritize them according to high priority numbers. Test scenarios, test cases, and test data are the basis of any testing process. A good tester will design them as per business needs.
  2. Data must be provided for every test case and requirement. The tester can use this information to execute the test case and check the code's hidden areas, the time taken by various operations, etc.
  3. After this, testing of internal modules takes place. Methods and interfaces are internal modules that can handle all types of data appropriately or not.
  4. Tests will be conducted on control statements such as conditional statements and loops to ensure efficiency and accuracy.
  5. By examining how the code handles security, the last step of White Box Testing includes a security check to ensure all possible security loopholes are closed by looking at how the code handles security.

Must Read, Locators in Selenium

Techniques for White Box Testing

There are mainly three types of testing techniques:

Statement Coverage

This testing technique tests all the defined programming statements. This determines the number of explanations executed in the source code of an application.

There are two criteria:

1. What are the test requirements?

These are the statements in the program.

2. How to measure coverage?

Coverage = (Number of Statements Exercised / Total Number of Statements) x 100% 


public class white_Box {
   public static void main(String[] args) {
       check(6, 4);
   private static void check(int x, int y) { //Statement 1
       if (x < y) {  //Statement 2
           System.out.println("x is less than y"); //Statement 3
       }  //Statement 4
       else {
           System.out.println("x is greater than y");  //Statement 5
       } //Statement 6


Test Case 1: x=4, y=6; “When x is less than y”

Total number of statements = 6
Total number of executed statements = 4
Statement coverage= 4*100/6;
66.0 %


Test Case 2: x=8, y=3; “When x is greater than y”

//Total number of statements = 6
//Total number of executed statements = 5
//Statement coverage= 5*100/6;
//83.0 %

Branch Coverage

This type of testing technique tests all the defined programming statements. 

Branch Testing = (Number of decisions outcomes tested / Total Number of decision Outcomes) x 100 % 

Path 1: 

No. of executed branches= 2

Total number of branches= 6 

Branch Coverage = 2*100/6;

= 33.3%


Path 2:

No. of executed branches= 4

Total number of branches= 6 

Branch Coverage = 4*100/6;

= 66.7%

Path Coverage

It is a testing technique corresponding to testing all possible paths, covering each statement and branch.

  • 1=>2=>3
  • 1=>4=>5=>6
  • Therefore the path coverage is 2

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White Box Testing Tools

Here are some open-source White Box Testing Tools:

  • JUnit: One Unit is primarily used for unit testing using a Java programming language.
  • PyUnit: Programmers utilizing Python can utilize PyUnit as a unit testing apparatus.
  • HtmlUnit: It allows program analyzers to mimic the functionality of a program by using HTTP decisions. Generally, combination tests are performed on online applications on other testing devices, such as JUnit.
  • Selenium: It allows web applications to be approved across various phases and programs with testing devices. JavaScript, Python, and C# are just some of the programming languages it supports.

Advantages and disadvantages of White Box Testing

Advantages of White Box Testing

  • The tester must know the internals of the software being tested.
  • By checking and working with internal functionality, it detects hidden errors.
  • Using White Box Testing, we can find issues and optimize the code to test a developed application or website.
  • In this sense, it helps in maximum code coverage since it requires internal knowledge.


Disadvantages of White Box Testing

  • Testing the internal structure of the system requires an experienced tester.
  • Time-consuming.
  • Expensive equipment is used.
  • You are required to perform code bit validation.

Difference between White Box Testing and Black Box testing

White-Box Testing

Black-Box Testing

It requires a complete understanding. Implementation knowledge is not required.
The white box testing process is straightforward. It can be challenging because tests and programmers are interdependent.
White Box Testing is primarily intended to check the quality of the code. This testing seeks to investigate the functionality of the system being tested.
Testing is done mainly by developers and testers. Tested by the end-user, the developer, and the tester
This method is exhaustive and time-consuming. It is less exhaustive and time-consuming.
This removes the extra lines of code that can introduce hidden defects. Suitable for large code segments.
Ideally used for testing algorithms. This method isn't the best for testing algorithms.
For White Box Testing, an experienced tester is needed. Testers without knowledge of programming languages and operating systems can test the application.
Code can rapidly change, making automated test cases ineffective. It is necessary to update automation test scripts frequently if you generally modify an application.



  1. Which technique is better White Box Testing or Black Box Testing?
    The black-box approach enables you to evaluate a system from the end user's perspective. You can focus on the intended customer journeys and test for expectations while ignoring the system's inner workings using Black box testing. Black Box testing is beneficial during product development and for the first few sprints after 'show stopper' bugs have been identified.
    In contrast with white box testing, you test the system from a developer's perspective.
    The process of studying the code specifications and fixing user journeys and scenarios that are considered an exception by end-users and can cause a lot of damage can be found in bugs that aren't caught by Black Box testing or other methods.
  2. When to perform regression testing?
    The QA department usually performs the test at the end of the product delivery process or before a significant release. In addition to complete regression, the root code also needs to be revised when the product requires significant functional or non-functional changes.
  3. When does a white box test fail, what are the consequences?
    As a result of a failure of white box testing, all black-box testing may need to be rerun, and white box testing paths might need to be reevaluated and changed.
  4. Why Are White Box Tests Called Glass Box Tests?
    Glass boxes are transparent. In white-box testing, the code is visible and is tested. However, in black-box testing, the tester has no idea what is happening inside the code when he provides an input. It is only the output he sees; he does not learn how it came into existence. In a white-box test, the tester can see what is exactly happening inside the code, as well as why a specific output corresponds to a particular input. Hence, it is called glass box testing.

Key Takeaways

Testing a software system's inner workings, such as its code, backend infrastructure, and integration with external systems is known as white box testing. It is also called Glass box testing, which is the opposite of black-box testing. 

White Box testing helps us verify logical conditions and in-correct/false result values.

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