White Box Testing


White Box Testing in SDLC

In this article, I am going to discuss White Box Testing in SDLC. Please read our previous article where we discussed Automation Testing. At the end of this article, you will understand the following important pointers which are related to White Box Testing in SDLC.

  1. What is White Box Testing in SDLC?
  2. What are the Objectives of White Box Testing?
  3. Types of White Box Testing in SDLC
  4. What to Verify in White Box Testing?
  5. How is White Box Testing Carried Out?
  6. What are the Different Techniques Used in White Box Testing?
  7. Tools used in White Box Testing?
  8. What are the Advantages of White Box Testing?
  9. What are the Disadvantages of White Box Testing?
What is White Box Testing in SDLC?

A software testing method known as “White Box Testing” focuses on looking at the internal workings and implementation specifics of the software under test. It is also known as structural testing, clear box testing, and transparent box testing. In white box testing, the tester has access to the software system’s internal code, algorithms, and design. As a result, they can produce test cases that focus on certain program logic, conditions, and paths.

Software developers or specialized testers who have access to the source code often carry out white-box testing. It complements other testing strategies like black box testing, in which the tester is unaware of how the software internally functions. Software engineers can improve the overall quality, dependability, and security of the software system by combining several testing techniques.

What are the Objectives of White Box Testing?

White box testing’s primary goals are to make sure of the following:

  1. Confirm the Accuracy of Internal Operations: White box testing looks at the internal logic, flow, and behavior of the code to confirm that the product works as intended. Designing test cases to disclose potential flaws, faults, or vulnerabilities requires analyzing the code to find them.
  2. Achieve the Highest Possible Code Coverage: White box testing seeks to achieve thorough code coverage by putting the code’s many pathways, statements, and branches to the test. Testing not only the program’s main flow but also diverse edge cases and extraordinary scenarios is the aim.
  3. Boost Software Performance: White box testing can locate areas that might have an impact on performance by identifying the underlying organization and algorithms of the software. Testers can assess the code’s effectiveness and resource utilization and make suggestions for performance enhancements.
  4. Validate Security and Robustness: White box testing can assist in locating software flaws and security holes. Testers can identify potential security holes and recommend solutions to strengthen the system’s resistance to attacks by carefully reviewing the code and how it interacts.
What Is the Focus of White Box Testing?

White box testing uses in-depth internal application knowledge to create test scenarios that are extremely focused. White box testing may involve the following types of tests, for instance:

  1. Path checking: To check that all conditional statements are accurate, required, and effective, white box testing can be used to investigate the many execution routes within an application.
  2. Output Validation: A function’s potential inputs are listed in the output validation process, which checks that each one leads to the desired outcome.
  3. Security testing: To find potential flaws in an application and confirm that it adheres to secure development best practices, static code analysis and other white box testing techniques are utilized.
  4. Loop testing: Loop testing verifies that an application’s loops are accurate, effective, and effectively manage the variables under their purview.
  5. Data Flow Testing: Verifies that variables are declared, initialized, utilized, and correctly manipulated by following variables along a program’s execution routes.
Types of White Box Testing in SDLC

White box testing can be used for a variety of reasons. There are three varieties of white box testing:

  1. Unit Testing: Unit testing is used to validate the functionality of each component or feature of an application. This makes it easier to make sure that during the development phase, the application complies with design criteria.
  2. Integration testing: Integration testing is concerned with how different parts of an application interact with one another. Following unit testing, it makes sure that each component not only functions well on its own but also that it can cooperate with other components to produce the desired result.
  3. Regression testing: Modifications have the potential to break an application. Regression testing ensures that the code still passes the earlier test cases after an application receives functionality or security updates.
What to Verify in White Box Testing?

The following aspects of the software code are tested during white box testing:

  • Intra-company security gaps
  • Paths in the coding processes that are broken or poorly organized
  • The way particular inputs are passed through the code
  • Anticipated result
  • Conditional loops’ capabilities
  • Each statement, object, and function is independently tested

The system, integration, and unit testing are all possible during the software development process. Verifying that an application’s working flow is one of white box testing’s fundamental objectives. It is comparing a sequence of specified inputs to desired or expected outputs in order to identify bugs when a particular input does not provide the desired outcome.

How is White Box Testing Carried Out?

We’ve divided white box testing into two straightforward stages to make it simpler for you to comprehend. Using the white box testing approach, testers do the following tasks when assessing an application:

  1. Understand the source code: A tester will frequently study and comprehend the application’s source code as their initial step. White box testing entails checking an application’s internal workings; therefore, the tester must have a thorough understanding of the programming languages used in the apps they are assessing. Additionally, the tester needs to be well-versed in secure coding practices. Often, one of the main goals of software testing is security. The tester should be able to identify security flaws and thwart assaults from hackers and gullible users who might willfully or accidentally introduce malicious code into the application.
  2. Creation of test cases and execution: The second key step in white box testing comprises checking the application’s source code to make sure it is organized and flows properly. Writing more code to test the source code of the application is one approach. For each procedure in the application—or set of processes—the tester will create a little test. This method, which is frequently carried out by the developer, necessitates that the tester has a thorough understanding of the code. As we shall discuss later in this article, other techniques include manual testing, trial-and-error testing, and the use of testing tools.

What are the Different Techniques Used in White Box Testing?

The following are some examples of white box testing techniques:

Statement Coverage:

With this technique, every single statement in the code is run at least once. To guarantee that each line of code is run during testing, test cases are created. A white-box testing technique called “statement coverage” seeks to make sure that each statement in a program is run at least once during testing. It calculates the proportion of the code that has been run through the test cases. Consider a straightforward example in order to clarify the idea. Suppose we have a function in a programming language called calculated that computes the addition of two numbers and returns the result:


White Box Testing in SDLC

def calculateSum(a, b):
if a > 0 and b > 0:
       result = a + b
      print(“The sum is:”, result)
      print(“Invalid input!”)

We want to write test cases for every statement in this code, which is known as statement coverage. Consider the following test cases:

Test Case 1: calculateSum(2, 3)
Test Case 2: calculateSum(-1, 5)
Test Case 3: calculateSum(0, 0)
Test Case 4: calculateSum(4, 0)

Let’s now examine how well these test scenarios are covered:

  • All of the statements in the code are run in Test Case 1. Within the if block, the print statement and the if condition are both executed.
  • The else block in Test Case 2 is executed, but the if block is not. Therefore, the coverage is lacking.
  • Neither the if block nor the else block is executed in Test Case 3. It doesn’t cover any of the code’s statements.
  • The if block in Test Case 4 is executed, but the else block is not. There is insufficient coverage.

The test cases in this sample covered the following ground:

75% of statements were performed (3 of 4 statements). We would need to create more test cases that cover the remaining statements in order to achieve 100% statement coverage. For instance, we may develop a test case that runs the code’s else block. Aiming for high statement coverage improves the chance of finding program faults or probable errors. It’s crucial to remember, though, that achieving high statement coverage simply assesses the thoroughness of statement execution and does not ensure the absence of defects in the code. Branch coverage and path coverage are two further white-box testing methods that can give more thorough coverage and identify more problems.

Branch Coverage:

This method makes sure that both the true and false branches of conditional statements are performed by testing every potential decision outcome. Branch coverage is a white-box testing approach used to assess how thoroughly a program’s branches have been tested. It seeks to make sure that every decision point or branch that could possibly exist in the code has undergone at least one test. Testers can feel confident in the software’s dependability and accuracy by achieving high branch coverage. Every decision point in the code is taken into account for branch coverage. An if statement, switch statement, or loop are common examples of decision points in code, which allow the program to choose between two or more options. Exercises are intended for both true and false decision-point outcomes.


White Box Testing in SDLC

Consider a straightforward example to show branch coverage. Let’s say we have a function that determines the highest value among two input parameters, x, and y:

function findMax(x, y):
if x > y:
      maxVal = x
      maxVal = y
return maxVal

We would need to create test cases that cover both the true and false outcomes of the decision point at line 2 in order to achieve 100% branch coverage. We could, for instance, develop the following test cases:

Test Case 1:

x = 5 y = 3

output anticipated: maxVal = 5 (True: Branch taken)

Test Case 2:

x = 2 y = 7

output anticipated: maxVal = 7 False (Branch taken)

We would exercise both branches (true and false) of the decision point by running these two test cases, completing full branch coverage.

Path Coverage:

A white box testing technique called path coverage makes sure that all feasible routes through a program or system are tested in order to assess how to complete test cases are. By testing each potential path from the beginning to the finish of a function, method, or program, it seeks to achieve maximum code coverage. All potential software pathways, including loops, conditionals, and nested structures, are tested as part of path coverage. This method makes certain that each potential execution path is examined.


Let’s explore an example to better grasp path coverage. Let’s say we have a straightforward function called “calculateSum” that takes two integer inputs and outputs their sum:

function calculateSum(a, b):
if a > 0:
      result = a + b
      print(“Sum is positive”)
      result = a – b
      print(“Sum is negative”)
return result

According to whether the sum of the two integers is positive or negative, the function outputs a message in the example below after computing the sum of the two numbers. We must test every execution path that is conceivable in order to achieve path coverage. There are several ways to use this function.

Path 1: a > 0 (true) ➡️ result = a + b ➡️ print “Sum is positive” ➡️ return result

Path 2: a > 0 (false) ➡️ result = a – b ➡️ print “Sum is negative” ➡️ return result

We would need to create test cases that cover both paths in order to achieve path coverage. For instance:

Case 1 of the test is calculateSum(2, 3).

This test case applies to Path 1: a > 0 (true), resulting in the printing of the message “Sum is positive”.

Case 2 of the test: calculateSum(-5, 2)

This test case applies to Path 2: the “Sum is negative” message will be printed if a > 0 (false).

What are the tools used in White Box Testing?

The best white box testing tools are listed below:

  1. EclEmma
  2. NUnit
  3. PyUnit
  4. HTMLUnit
  5. CppUnit
What are the Advantages of White Box Testing?

The following list of benefits of white box testing can be summed up:

  1. Test Coverage: White box testing enables thorough test coverage by allowing testers to inspect the internal logic, structure, and implementation details of the software.
  2. Early Issue Detection: White box testing makes it easier to find bugs and vulnerabilities at an early stage of the development process by giving you access to the source code.
  3. Targeted Test Design: To maximize the efficacy of testing efforts, test cases can be deliberately created to target important parts of the code.
  4. Optimizes Code and Boosts Speed: White box testing helps find inefficient algorithms or resource-intensive operations, which optimizes code and boosts speed.
  5. Greater Understanding of the Code: Testers develop a deeper understanding of the program architecture, allowing for more efficient troubleshooting and future maintenance.
What are the Disadvantages of White Box Testing?

The following list of disadvantages of white box testing can be summed up:

  1. Time-Consuming: White box testing is time-consuming because it entails examining the software’s internal architecture, which takes a lot of time and effort.
  2. Test Coverage Lacking: White box testing offers thorough coverage of the internal code, but it may ignore external aspects and user interactions, leaving the test coverage lacking.
  3. Dependence on Implementation Details: Because white box testing is so dependent on understanding how the software functions internally, it is less successful when there are frequent code updates or when the internal organization is complicated.
  4. Ability-Required: White box testing is only accessible to testers with significant programming abilities, making it inaccessible to non-technical testers.
  5. Insufficient Requirement Validation: White box testing may place more emphasis on checking the functionality of the code than determining if the product satisfies the intended requirements, potentially ignoring important issues.

In the next article, I am going to discuss Black Box Testing in SDLC. Here, in this article, I try to explain White Box Testing in SDLC. I hope you enjoy this White Box Testing in SDLC article.

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