White box testing

What is white box testing?

White box testing evaluates an application to ensure it performs according to specifications. White box testers have visibility into or knowledge of the code, design, and structure of the software they’re testing along with a view of how it integrates with external systems. This insight allows them to design tests more accurately and thoroughly.

White box testing can be used to look for:

• Expected or unexpected output, ensuring that all possible inputs to a function return the expected result
• How specific inputs flow through the code, tracking variables and values as they pass through the code to find instances where they may not be correctly manipulated, initialized, or where they are declared but never used
• Broken or poorly structured paths that contain a redundant, broken, or inefficient conditional logic
• Loop functionality, checking the efficiency, conditional logic, and the correct variable handling in single loops, concatenated loops, and nested loops
• Security gaps and vulnerabilities that may make the application vulnerable to threats and exploits

How white box testing is performed

White box tests are performed in two basic steps.

1. Understand the source code. White box testers must be fluent in the programming languages used by the software they’re testing and steeped in secure coding practices. White box testing begins by analyzing and understanding the application’s source code, design, and structure so that appropriate test cases can be created.
2. Create and execute test cases. Once testers have analyzed the application’s code and structure, they write additional code to test various aspects of the system’s flow and structure. Testers may also use a variety of testing tools to perform automated tests.

Type of tests and techniques

White box testing comprises several types of tests and testing techniques.

Types of white box tests

• Unit tests are performed to ensure that each component of an application works as expected.
• Integration tests confirm that internal components or integrations with external systems work as expected.
• Static code analysis automatically identifies errors or vulnerabilities in static code.
• Memory leak tests seek to uncover leaks that may cause applications to run slowly.
• White box penetration tests deploy ethical hackers who attempt to attack an application using detailed knowledge of its code.
• Mutation tests evaluate the consistency of code by defining tests and then making small, random changes to the code and seeing if the test still works.

White box testing techniques

• Code coverage makes sure that the source code is tested as comprehensively as possible.
• Statement coverage tests every possible statement in the code at least once as the software is developed.
• Branch coverage checks every possible path within an application, including if-else and other conditional loops.
• Condition coverage evaluates each individual condition.
• Multiple condition coverage tests all possible combinations of conceivable condition outcomes.
• Path coverage tests every probable path in the code.
• Function coverage evaluates the number of defined functions that have been called and uses different input parameters to determine that the logic of the functions behaves as intended.
• Data flow testing tracks data variables to verify their use, uncovering bugs related to variable initialization or variables declared but not used.

Advantages and disadvantages of white box testing

Advantages of white box testing include:

• Early testing. White box testing can start early in the software development lifecycle, even before a GUI has been developed.
• Automation. White box tests can be automated easily to improve coverage with less effort.
• Coverage. White box tests are more thorough than black box testing, as tests typically cover all code paths.

Disadvantages of white box testing:

• Complexity. Managing white box testing can be complicated and costly.
• Lack of objectivity. Because testers have knowledge of how the application works, it doesn’t allow them to test from the user’s perspective.
• Updates. Updates to code can invalidate test cases, requiring white box testers to spend a great deal of time creating new cases.

White box testing with Tricentis

Tricentis provides a new and fundamentally different way to manage software testing, dramatically accelerating digital transformation, cloud migration, and application delivery. With an approach that is fully codeless, totally automated, and driven by AI, Tricentis enables development teams to manage testing in minutes or hours rather than days or weeks, supporting continuous integration and continuous delivery.

Tricentis qTest is a enterprise test management tool that integrates seamlessly with DevOps and third-party test tools to manage white box testing and many other types of software tests in one place. Tricentis qTest helps to unify, manage, and quickly scale testing across the enterprise, allowing teams to collaborate more easily and release software faster with less risk.

With qTest, development teams can:

• Standardize and accelerate testing at scale by reusing test cases across projects
• Easily manage manual testing, exploratory testing, and automated testing as well as chaos engineering and many other types of tests
• Support Agile, DevOps, and Waterfall workflows to guide transformation across the enterprise
• Integrate and automate with every part of the DevOps toolchain
• Keep QA and development in sync with native DevOps tool integrations including Jenkins
• Accurately identify test gaps and measure coverage with a complete view of testing activities from development to production
• Help support audit and compliance needs with granular test data and full traceability to requirements
• Centrally manage open source frameworks and commercial test automation tools
• Plan and organize testing activities through every part of the development lifecycle and software testing lifecycle