What Is White Box Testing?

White box testing ensures that software meets organizational needs and is vital to the software verification process. It helps professionals like software developers and testers understand the inner workings of software. This method allows you to see inside the code to find any errors that may prevent a program from running as intended. 

Read on to explore white box testing, its importance, the different types, and how to perform it.

professional certificate

Google Cybersecurity

Get on the fast track to a career in cybersecurity. In this certificate program, you'll learn in-demand skills, and get AI training from Google experts. Learn at your own pace, no degree or experience required.

4.8

(39,963 ratings)

858,170 already enrolled

Beginner level

Learn More

Average time: 6 month(s)

Learn at your own pace

Skills you'll build:

Python Programming, Security Information and Event Management (SIEM) tools, SQL, Linux, Intrusion Detection Systems (IDS), Packet Analyzer, Security Hardening, Network Security, Transmission Control Protocol / Internet Protocol (TCP/IP), Network Architecture, Cloud Networks, escalation, resume and portfolio preparation, stakeholder communication, Job preparedness, integrity and discretion, Cybersecurity, Information Security (INFOSEC), Ethics in cybersecurity, NIST Cybersecurity Framework (CSF), Historical Attacks, Computer Programming, Coding, PEP 8 style guide, NIST Risk Management Framework (RMF), Security Audits, Incident Response Playbooks, Authentication, vulnerability assessment, Cryptography, asset classification, threat analysis, Command line interface (CLI), Bash

What is white box testing?

White box testing is a type of software verification performed to check a software program’s operation and ensure it’s consistent with the developer’s design. This testing method may also be called clear, open, or glass box testing.

White box testing focuses on transparency and insight. It looks at an application’s internal workings, including the architecture, design, and code. White box testing is used in many industries to verify that technology works properly. Examples of white box testing include: 

• An electrical engineer looking closely at each circuit and connection in an electrical system

• A software engineer running each section of a code individually

Read more: What Is a QA Manual Tester? Skills, Job, Salary, Career Path

White box testing vs. black box testing

White box and black box testing have different approaches, however, both are essential in ensuring that software runs smoothly and meets user needs.

As mentioned, white box testing is a code-based testing method that is like peeking inside a transparent toy to understand its mechanics. Testers look inside the software’s actual code, structure, and workings. This method gives a clear view of the internal processes, allowing them to identify specific areas where errors might occur.

Conversely, black box testing doesn’t require knowledge of the internal mechanisms. Imagine testing a toy without looking inside, just observing its performance. In this approach, the tester doesn’t see the software’s code. Instead, they focus on inputs and outputs, ensuring the software behaves as expected without knowing how to get those results.

Both methods are important and offer unique perspectives. While white box testing confirms the internal structure and workings are sound, black box testing validates that the program works as expected to meet the end goal.

When to use white box testing

Whether you should apply white box testing depends on the testing phase and available resources. Consider using it in the following scenarios:

• A deep understanding of the application is required: When you need to understand the software deeper, white box testing can be the right choice. This type of test focuses on the system's internal logic, providing insights that black box testing might miss.

• Security audits: White box testing can be a great fit to ensure software is free from vulnerabilities or potential breaches. By examining the code, testers can spot security flaws that might not be immediately visible during an external test.

• Optimization: If the goal is to optimize performance, white box testing can pinpoint inefficient sections of code or processes that can be streamlined. It helps developers ensure they have the most effective performance and design.

course

Introduction to Test and Behavior Driven Development

Successful developers need to not only build the right software but build it right. To know your software works correctly, you need to test each unit of ...

4.8

(223 ratings)

24,851 already enrolled

Intermediate level

Learn More

Average time: 19 hour(s)

Learn at your own pace

Skills you'll build:

Software Engineering, Software Testing

Types of white box testing

You can choose between several types of white box testing. Depending on your code structure and test cases, you might use the following types of testing.

1. Path coverage testing

Path testing aims to check that you can follow every pathway in the software without hitting a dead end. It verifies each possible route through the code and tests that all paths are accurate and reliable.

2. Loop testing

Loop testing checks a code’s function and logic of loops, including individual, nested, and concatenated loops. This method assures testers that the code follows the appropriate flow and that variables are handled correctly when inputted into the program.

3. Integration testing

Integration testing determines whether all code units function together as expected. If you don’t perform this testing, you may find issues when these units interact or integrate with each other or external systems. 

4. Unit testing

Unit testing focuses on the building blocks. You’ll test each small part (or “unit”) of the software in isolation to ensure it works perfectly. You may compare it to testing individual ingredients before you mix them into a recipe. By validating each component separately, it becomes easier to pinpoint issues and verify the overall system’s reliability.

5. Mutation testing

Developers deliberately introduce minor errors or “mutations” into the software code for mutation testing. If the tests detect these intentional faults, they indicate their robustness—if they miss them, they highlight potential gaps in the testing process. Think of it as a self-check mechanism for testing procedures, ensuring they’re as thorough and effective as intended.

Benefits and drawbacks of white box testing

Here is a breakdown of the advantages of white box testing: 

• Comprehensive coverage: White box testing ensures that every part of the code is tested. This thoroughness translates into a higher likelihood of spotting bugs and inconsistencies.

• Opportunities for optimization: By examining the code’s intricacies, you can identify any inefficiencies or redundancies, paving the way for performance improvements and code optimization.

• Better code understanding: White box testing offers developers deeper insights into the code. This familiarity can lead to better design decisions and improved coding practice in future projects.

• Enhanced security: Once you understand the code’s structure, you can identify potential security loopholes and vulnerabilities, making the software more secure.

• Increased automation: With a deep knowledge of the code structure, it becomes easier to automate white box tests, making recurrent testing more efficient.

As you consider which type of testing to use, here are several drawbacks to remember.

• Increased complexity: White box testing, which requires an in-depth analysis of the code’s internal structures and logic, can become complex, especially for large software systems. 

• Fragility in test cases: As white box testing is deeply tied to the internal code, even minor changes in the codebase can warrant frequent updates.

• Advanced knowledge required: Because white box testing relies on knowledge of the software's internal structures, performing this type of test requires more knowledge and expertise than alternate software tests, such as gray box or black box tests.

course

Introduction to Test and Behavior Driven Development

Successful developers need to not only build the right software but build it right. To know your software works correctly, you need to test each unit of ...

4.8

(223 ratings)

24,851 already enrolled

Intermediate level

Learn More

Average time: 19 hour(s)

Learn at your own pace

Skills you'll build:

Software Engineering, Software Testing

Steps to perform white box testing

While exact steps vary, you can follow this general guide to begin white box testing. Depending on your program, you may choose different types of test cases.

Step 1: Write or familiarize yourself with the code.

The first step is to write or familiarize yourself with the source code. As white box testing relies on knowledge of internal structures, thinking about possible paths and test cases as you develop the code can help inform the next steps of the process.

Step 2: Create a test case design.

Test case design involves testers crafting specific scenarios to evaluate the software code. Programmers choose specific test designs to check statement, branch, and loop coverage and confirm that the program runs as designed.

Step 3: Execute the test.

In the test execution phase, you’ll run the previously designed test cases on the software. You can use automated tools to facilitate this process, especially if the software is extensive or the number of test cases is large.

Step 4: Repeat tests.

After identified issues are addressed, you can repeat tests to meet the desired standards.

Step 5: Retest for regressions.

Once the issues are fixed, regression testing ensures the new changes haven’t introduced bugs or negatively impacted the software’s existing functionalities.

Learn how to white box test

Become familiar with software analysis, testing, and programming languages before starting white box testing. 

Understand the basics of programming.

Before software testing, having a solid grasp of programming concepts is beneficial. Practice and become proficient in a popular programming language such as C#, Java, Python, or C++. You'll gain insight into the inner workings of a software program. 

Learn about the software development life cycle (SDLC).

The software development life cycle (SDLC) refers to the steps required to create high-quality software. These include analysis, planning, maintenance, and more. The SDLC process provides clear steps for producing software. 

Next steps with Coursera

If you’re interested in starting a career in cybersecurity with software testing, consider the Google Cybersecurity Professional Certificate on Coursera. This program is designed ​​to help individuals with no previous experience find their first job in the field of cybersecurity, all at their own pace. The courses cover topics such as security models, tools that are used to access and address threats, networks, and more. Upon completion, gain a shareable certificate to include in your resume, CV, or LinkedIn profile.

professional certificate

Google Cybersecurity

Get on the fast track to a career in cybersecurity. In this certificate program, you'll learn in-demand skills, and get AI training from Google experts. Learn at your own pace, no degree or experience required.

4.8

(39,963 ratings)

858,170 already enrolled

Beginner level

Learn More

Average time: 6 month(s)

Learn at your own pace

Skills you'll build:

Python Programming, Security Information and Event Management (SIEM) tools, SQL, Linux, Intrusion Detection Systems (IDS), Packet Analyzer, Security Hardening, Network Security, Transmission Control Protocol / Internet Protocol (TCP/IP), Network Architecture, Cloud Networks, escalation, resume and portfolio preparation, stakeholder communication, Job preparedness, integrity and discretion, Cybersecurity, Information Security (INFOSEC), Ethics in cybersecurity, NIST Cybersecurity Framework (CSF), Historical Attacks, Computer Programming, Coding, PEP 8 style guide, NIST Risk Management Framework (RMF), Security Audits, Incident Response Playbooks, Authentication, vulnerability assessment, Cryptography, asset classification, threat analysis, Command line interface (CLI), Bash