10 best practices for White Box Testing

Automation Testing

Testing is the most challenging activity in the development of software. It is done to ensure the quality of the product before being delivered to the end user. Among the different types of testing approaches, practice for White Box Testing is considered the functional testing method.  

Practice for White Box Testing is performed by the software developer or the person with the knowledge of the coding language of the application. It is the approach of testing the program’s core design and internal structure and analyzing the code. It allows the developers to look at the code’s structure, which helps ensure that internal operation is in line with the specification. 

Further, White Box Testing also evaluates the internal component, which has been adequately performed. The present blog will discuss the ten-best practice of White Box Testing, which will help you in your work as a tester. 

Overview of the White Box Testing

White Box Testing allows code tested to be visible to the tester; hence also named Clear Box Testing, Transparent Box Testing, Open Box Testing, Glass Box Testing, and Code-Based Testing. Thus, due to the see-through concepts, the name specifies the ability to observe the out shell of the software and related workings. 

It detects different software errors like defective algorithms, omission, and logic errors proceeding by verifying the input-output flow, security, usability, and improvising the design. In software QA testing, practices for White Box Testing are one of the parts of the method, whereas the other part is called Black Box Testing. 

Few highlights on White Box Testing

  • It determines the appropriateness and accuracy of the output of the program. 
  • It allows for analyzing and investigating the program’s source code and its different parts in the testing process. 
  • It can test many different programs like C/C++, Java, and others.
  •  It is cited in the Static Application Security Testing (SAST) framework that automatically checks the source code and binaries while providing feedback on the bugs and related vulnerabilities. 
  • White Box Testing provides inputs and investigates outputs while considering the code’s inner workings.
  • It discovers the logical error, design errors, and typographical errors. 

Area of focus of the White Box Testing 

The following issues are identified while using the White Box Testing: 

  • Expected output: Different potential inputs are tested for a certain function to analyze if the expected results are similar. 
  • Loop testing: checks if the concatenated loops, nested loops, and single loops are efficient. 
  • Data Flow Testing: It allows monitoring of the variable and related values while going through the codes in order to recognize the one which is not appropriately initialized. 
  • Security gaps: It checks the code against the security implemented for the application. 

Here are some ten best practices for White Box Testing 

  1. The software being tested needs to be understood

The software developer and tested are required to have a sound working knowledge of the system in which the test is being performed. The main reason for the above is that it helps to get a better idea of the software, thus, specifying the tests conducted. To accomplish that, you can refer to the design document and utilize the source code browser and UML diagrams. Other approaches could be using the framework or libraries of the project. 

  1. Functional Decomposition of software to be tested

In White Box Testing, decomposition is crucial as it reduces the system into its different parts. In other words, it breaks the complex functionality into simple and smaller parts. It is done to recognize the part of the system that requires testing. It is also useful in giving an idea of the use of the methodology and technique in line with the decomposition approach. The steps involved in the functional decomposition include: 

  • Finding general function 
  • Finding closet sub-functions 
  • Finding the subsequent levels of sub-functions 
  • Validating the functional decomposition diagram 
  1. Understanding the source code explicitly

The most priority task that a tester should learn and gain an in-depth understanding of is the application’s source code. Addressing the fact that White Box Testing involves an examination of the inner functioning of the application, it is significant that the tester is knowledgeable in the programming language that has been used in the application being tested. The knowledge of secure coding practice is equally important for the testers.  

In White Box Testing, security is the critical issue that needs consideration. The tester needs to be able to find the security issues in order to prevent the attack of malicious code on the application. This could be done efficiently when the tester is aware of the source code. 

  1. Creating and executing the test cases

One of the major steps in White Box Testing is examining the source code of the application secondary to its flow and structure. It could be accomplished by the practice of writing the code in order to test the source code of the application. For each process of the application, the tester tends to develop tests. However, this tester should have comprehensive knowledge of the code; or the developers mainly perform it. 

  1. Use of Code Coverage analysis

It is a White Box Testing technique that allows the elimination of the test case suite. It recognizes the aspects of the program which are not executed by a test case. When the tester successfully identifies the gap, the test cases can be created to validate the untested parts of the code. Hence, this leads to an increase in the quality of the application. 

Below are the explanations for the coverage analysis technique: 

  • Statement coverage: A statement in a programming language is just a line of code that help the system to understand and act. On being compiled and changed to object code, it turns into the executable statement that acts while the program is running. It signifies whether each line of the code is executed at least once. Its main aim is to verify and validate unused branches, missing statements, dead codes, and unused statements. 
  • Branch coverage: In a programming language, “branch” is similar to IF statement, which mainly has two branches, for example, true and false. With branch coverage, validation on each of the branches has executed a minimum of one time is tested. Hence, it checks every possible path of the software application. As part of the practice for White Box Testing, the testers map the codes in diverse branches of the conditional logic to cover all conditional and unconditional branches. It helps them to write the code to perform as many of such branches as possible. 
  • Path coverage: It allows testing of all parts of the program. This technique confirms that all the paths of the program are traversed a minimum of one time. It is mainly utilized for testing the complex program. The control flow diagram of the code is mapped by the tester which is later utilized to structure the test in this approach. The primary aim of the practice is to identify broken, redundant, and inefficient paths.
  1. Control flow testing:

It is a crucial practice for White Box Testing that finds the executed order of statement of the program by the use of a control structure. The utilization of the control structure of the program allows the development of test cases. In the use of this technique, from a large program, a specific part is selected by the testers in order to set the testing path. The control graph of the program mainly presents the test cases. The use of node, decision node, edge, and junction node is done in forming a control flow graph in order to highlight all the possible executed paths. An example of the flow graph notation is given below, where each node signifies a sequence of statements.

  1. Use of different White Box Testing Tools

The use of different tools for performing White Box Testing is also considered to be the best practice. There are a number of White Box Testing tools, and you can choose any as per your requirement. Some of them are as follows: 

  • JUnit.net: It is a JavaScript testing tool and is considered the unit testing apparatus. It is open source and used to do White Box Testing by using Java programming language to analyze the programs. 
  • PyUnit: It is also considered the unit testing apparatus that uses the Python programming language to analyze the program. 
  • Veracode: It is a White Box Testing tool that helps in finding and resolving any errors and bugs quickly at a low cost. It is well known for its ability to support different languages like .NET, C++, JAVA, etc. It further helps in ensuring the security of the web and mobile applications. 
  • Selenium: It is the set-up of testing the devices to affirm web applications over different programs and stages. LambdaTest is a platform that allows testing websites across 3000+ browser, operating system and device combinations on the cloud by allowing the running of selenium scripts on the cloud. Thus, it gives end-to-end test execution to analyze detailed selenium test logs.  
  1. Use of loop testing

Loop testing is performed to validate the loop in the program in White Box Testing. Loop can be understood as the instruction sequence that runs continuously until a certain situation or condition is reached. It mainly focuses on correcting the loop structure of the application. It is a component of Control Structure Testing. The main aims of loop testing are to solve the issue of endless loop repeating, be conscious of the performance, find an error in the startup of the loop and investigate any uninitialized variable. It is categorized into three types: 

  • Simple loop testing
  • Nested loop testing
  • Concatenated loop testing
  • Unstructured loop testing 
  1. Make use of stubs and drivers

In practice for White Box Testing, the utilization of the stubs and drivers to test on the basis of its interface is done. Stubs are used in the Top-Down integration, and drivers are used in Bottom-up integration testing. Such elements surge the efficiency of the testing process. It allows the testers to determine the expected working of the code at the interface by simulating testbeds. Decision table testing or data flow testing can be utilized for such practice for White Box Testing. 

  1. Use of path testing 

Path testing in a White Box Testing is the technique used to control the structure of the program and module. This also involves preparation for the control flow graph that portray different path in the graph and its execution as part of White Box Testing. This practice helps build and test all the possible paths within the code of the tested program. It allows determination of the accuracy in working of the system with the error at the limits or boundaries of the input domain. 


In the testing approach, practice for White Box Testing is considered a valuable means to test the internal coding and infrastructure of software. Although White Box Testing may be expensive and time-consuming, it is considered to be the only way to ensure that all the code’s parts are included in the process of testing. For the execution of White Box Testing, it is essential to have good knowledge of source code and programming language; otherwise, it may cause trouble in testing. 



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