Why White Box Testing is an Essential Part of Software Testing

Organizations today are working smartly to find the right approach to software testing since it is one of the inevitable parts of any software development life cycle. It is observed that the right approach to testing often blends the ideal mix of different testing techniques to ensure all the aspects of a software are tested thoroughly.

Box testing, with its two essential types, white box, and black-box testing, is one of the widely used software testings as you must know.

Talking in detail about white box testing, let’s begin with the definition.

What is White Box Testing?

White box testing is a type of software testing that tests the source code and the internal structure of a program rather than its functionality. It focuses on the inner workings of the code to ensure that all the internal components work as expected and are error-free. It is also known as clear box testing, glass box testing, or structural testing.

Basic Steps to Perform White Box Testing

White box testing allows the tester to access the source code and test it from the developer’s point of view. Although, both developers and testers can perform it. It is performed in the following manner:

1. Preparation and input: For white box testing, a tester must be well acquainted with the programming language to understand the code being tested better. It allows the tester to analyze the source code and create test cases for every visible path. The inputs involved are functional specifications, design, security specifications, types of requirements, and the source code.
2. Create and execute tests: With all the technical details acquired, the tester will now create tests for all the possible scenarios that the program is designed to handle and run them.
3. Output: After running the tests, the tester prepares a detailed final report that includes all the above testing preparations and test results.

White box testing can be applied to unit testing, integration testing, and system-level testing phases of the software testing process.

White Box Testing Techniques

A fundamental principle that helps in the successful execution of white-box testing is Code coverage. Code coverage measures up to what extent an application’s code has been tested.

Here are the prominent white box testing techniques that help in maximizing code coverage:

• Statement Coverage: This technique ensures that every executable line of code is tested at least once. It helps point out incorrect code, unused statements, unused branches, or dead code.
• Branch Coverage: It aims to ensure that each branch from all decision points is tested. For example, there will be two test cases for both true and false branches in an IF statement.
• Function Coverage: It aims at ensuring that the logic of the functions behaves as expected. It assesses the number of defined functions that have been called.

There are also numerous other white box testing techniques such as path coverage, multiple condition coverage, and others that help maximize coverage.

Why is White Box Testing an Important Element of Software Testing?

White box testing plays a vital role since it allows a tester to run all the possible permutations and combinations. It ensures that the code works as expected and there are no surprises later on, thus building robust software. Testing software at the most granular level can also help strengthen and improve its security, usability, and design.

White box testing is performed to:

• Ensure every independent path in a module is exercised at least once
• Discover logical or design errors that can occur during actual implementation
• Discover any security gaps or vulnerabilities in the code
• Identify broken or inefficient paths and redundant conditional logic
• Check typographical errors and syntax

White box testing can bring out bugs that otherwise might not be caught in Black box testing or other software testing methodologies. Today, it has become an essential part of the automated build processes of the modern CI/CD pipeline.

It is a must for complex, mission-critical systems and components. It gives attention to detail and ensures the code is bug-free with extensive testing. Although you cannot rely exclusively on white box testing for the quality assurance of critical systems, it is one of the most indispensable techniques.

Advantages of White Box Testing

• It can be started at an earlier stage in SDLC as it doesn’t require any interface
• Easy to automate
• Thorough testing of entire code and structures
• Allows for continuous improvement and optimization of code
• Testers get acquainted with code’s internal workings, which reduces communication overhead between them and the development team
• It helps achieve high code coverage when combined with other techniques
• Allows future changes in the source to be captured easily by providing traceability of tests from the source

Wrapping Up

White box testing is a comprehensive testing technique that can help the development team build quality software. Although, it can prove to be complex and time-consuming for large projects. But today, there are many tools available supporting a wide range of programming languages that can make white box testing easier.

Knowing when to go for it is the key to doing white box testing right. It depends on the maturity of the system being tested, the tester’s experience, the stage in SDLC, or whether you’re trying to improve code quality. Use it wisely with a mix of other testing techniques, but make sure not to skip it!