Testing an application software at all levels to deliver a quality product is key to its success. Software testing techniques have evolved over the years and have become more stringent, quick (through automation), and reliable at the same time. Quality has become an integral part of the development cycle.

However, just testing the functionalities of software under different scenarios alone is not enough. There is a need to test data structures, code structures, and internal design of the application software. In a nutshell, this is what white-box testing is all about. It is also known as open box testing, glass testing, or even clear box testing.

One of the main aspects of white box testing is being able to test the internal structure, which means that a tester is looking inside from outside.  A tester will have to study the code line by line and validate the inputs and outputs of the software. This means that the tester also needs to have a good understanding of programming. Strong coding and implementation information are crucial in white box testing. On the other hand, black box testing is always done from a user’s perspective.

White Box testing validates the quality along with the accuracy of the system. It can be applied at various levels of testing including unit testing, integration testing, and regression testing. Let us try to understand what is included in white box testing:

• Identifying poorly constructed code structures
• Identifying internal security issues
• The flow of inputs through the code path
• Study the entire code for loopholes
• Functions of the conditional loops

However, what we need to understand is that white box testing may not be useful everywhere. Though it can be implemented on any software, it is highly recommended for mission-critical applications. When we say mission-critical, we mean life-altering events that may occur. In such scenarios, having bugs or errors is not even an option. Even minute aspects of the code are tested, it exposes errors and helps in improving the application software to perform at the highest level of efficiency.

Understanding the process of White Box testing

The key aspect of white box testing is the analysis of code coverage. It allows you to identify gaps and be able to fix them to improve the performance of the software. Once the gaps are identified, test cases have to be created based on the identification. To understand it better, the entire process can be broken down into four parts:

Required inputs- this includes specifications, requirements, design documentation, and the source code of the application.

Process- performing risk analysis

Preparing test cases- preparing the test cases that cover the entire code.

Generating Outputs: This step includes generating the outputs of the tests that were performed, compiling the reports.

Different Techniques of White Box Testing

Statement Coverage: The tester has to go through all the statements (represents lines of code), covering all code to ensure there no errors or bugs. Any failures can be uncovered this way and maximum code coverage can be achieved. The idea here is to execute each line of code at least once.

Branch Coverage: A branch is a set of instructions that includes an “If” clause. An “If clause” contains two branches i.e. success or failure. Here all the test cases are prepared in such a way that all branches of each edge point will be executed at least once.

Condition Coverage: All possible permutation combinations and their outcomes are tested throughout the application software at least once.

Path Coverage: It entails covering all paths that are covered in the test at least once. This technique is vital while testing complex products.

Advantages of incorporating White Box Testing

• One of the major advantages of white box testing that we have established so far is that we can achieve complete code coverage
• Ideal for complex software
• Optimizing code after identifying the errors
• It can be started as early as possible in the development cycle
• White box testing can easily be automated as well
• Removing unnecessary codes becomes easier

Disadvantages of White Box Testing

• One of the key drawbacks is that it cannot detect missing functionalities in the software
• Testers need to have in-depth knowledge of programming
• Conducting white box testing can also be expensive
• Rewriting the code requires the testers to then update the test cases
• Tools may not be readily available for every platform
• It is time-consuming to execute

Even though it is complex to execute, white box testing can be the backbone of testing of complex applications. eInfochips with over 25 years of experience has a complete end-to-end product testing and product development capabilities. To know more about our Quality Engineering capabilities, talk to our team of experts today.