Dynamic White Box Testing is a software testing strategy that evaluates an application's internal structure or workings while it runs. This form of testing is dynamic because it involves executing the code during the test.

The tester needs a deep understanding of the code to test the application's internal structures and workings. Dynamic White Box Testing effectively identifies hidden errors, verifies the internal operations of a system, and ensures the correctness of the expected outputs.

This blog teaches you about Dynamic White Box Testing, its key features, how White Box Testing works, its levels, success stories of implementing white box testing, techniques, and the tools & technologies commonly used for Dynamic White Box Testing.

Let’s get started.

What is Dynamic White Box Testing?

Dynamic White Box Testing, also known as Dynamic Structural Testing, involves the tester knowing the application's internal structure and workings. Testers execute the software code to validate its behavior and check for functional correctness, code coverage, and other attributes by observing the program’s runtime behavior.

It helps verify a system's internal operations and ensures that the expected outputs are correct. Dynamic White Box Testing is complex because the tester needs to know the codebase's internal workings.

Key Features of Dynamic White Box Testing

Dynamic White Box Testing encompasses several key features that distinguish it from other testing approaches:

1. Inspection of Internal Structure

While black box testing examines how the software works without revealing what happens inside, dynamic white box testing lets testers examine what's inside the software. This allows them to examine the code, understand the data structure, and see how the software tackles issues.

2. Path Analysis

Testers identify and test the paths through which a program transfers and transforms data. White box testing aims to reveal potential errors or something abnormal related to the data flow, such as incorrect assignments, missing data updates, and data dependencies.

3. Code Coverage Analysis

A critical feature of dynamic white box testing is the ability to analyze code coverage. This process identifies the untested areas of the code, thereby ensuring a thorough evaluation of the entire codebase.

In code coverage analysis, you must verify that the software's internal design follows the designated design documents and that the code operates according to the guidelines and specifications.

4. Optimization of Code

Dynamic white box testing identifies performance issues, redundant code, or other areas for improvement by analyzing the software's internal structure and execution paths in detail.

How Does White Box Testing Work?

White box testing involves testing the internal operations of a system. Here's a simplified explanation of how it works:

1. Understanding the System

The tester must first understand the system's internal operations comprehensively. This crucial process involves a deep and thorough understanding of the system's code, the algorithms that drive its functions, and the data structures it utilizes in its operations.

2. Creating Test Cases

The tester creates test cases based on their understanding of the system. These test cases test different system parts, including logic, data flow, and overall functionality.

3. Running Tests

Once the tester has crafted and prepared the necessary test cases, they proceed to execute these tests. As the name 'dynamic' suggests, the system under test will be in an active execution state during this testing phase.

4. Analyzing Results

After running the tests, the tester examines the results. They will check whether the system's actual outputs match the expected outputs for each test case. Any differences indicate a potential issue in the system.

5. Fixing Issues

If the tester identifies any issues during the testing process, they report them to the development team. The development team can then use this information to fix the identified issues.

Levels of Dynamic White Box Testing

Dynamic White Box Testing has different levels, each focusing on different aspects of the software's internal structure. These levels include:

1. Unit Testing

The first level focuses on individual components or parts of the software. It ensures that each unit of the software works as intended. Identifying and resolving issues at the earliest stage of development is crucial.

2. Integration Testing

This level tests how well different units of the software work together. It ensures smooth and error-free interaction between different software parts and validates that the integrated units function together without causing disruptions or failures.

3. System Testing

System testing evaluates the software system against defined requirements to confirm its proper functioning. This testing level generally checks the software's functionality, performance, and user-friendliness.

4. Acceptance Testing

The final level tests whether the software meets the end user's needs and expectations and determines whether it is ready for release. This step ensures customer satisfaction and successful deployment.

Dynamic White Box Testing Examples

Let's explore some real-world examples where organizations have successfully used Dynamic White Box Testing to enhance software quality and reliability:

1. Microsoft: Improved Code Quality and Security

Microsoft has extensively used dynamic white box testing to improve the quality and security of its software products. By integrating dynamic white box testing techniques in their software development lifecycle, they have identified and resolved numerous bugs and security vulnerabilities early in the development process.

2. Google: Enhanced Reliability of Google Chrome

Google employs dynamic white box testing to ensure the reliability and security of its web browser, Google Chrome. By thoroughly testing the browser's codebase, Google identified and fixed potential performance, security, and functionality issues before they affected end-users. This rigorous testing approach has contributed to Chrome's reputation as a fast, secure, and reliable browser.

3. NASA: Ensuring Safety-Critical Software

NASA uses dynamic white box testing to ensure the safety and reliability of software used in their space missions. For example, the software systems for the Mars Rover and other spacecraft undergo extensive dynamic white box testing to detect and fix any potential issues that could risk the mission.

Techniques of Dynamic White Box Testing

Dynamic White Box Testing employs several techniques to test and analyze the internal structures of an application. Here are a few of those techniques explained:

1. Statement Coverage

Testers achieve Statement Coverage by running all the executable statements in the code at least once. This technique ensures the execution of each line of code during testing, but it doesn't guarantee that every logical path is tested.

Example: Consider a function that categorizes an age into different stages:

def categorize_age(age):
    if age < 13:
        return 'Child'
    elif age < 20:
        return 'Teen'
    elif age < 60:
        return 'Adult'
    else:
        return 'Senior'

Statement coverage would require tests to ensure each return statement executes at least once.

2. Condition Coverage

Condition Coverage requires the evaluation of each Boolean sub-expression in a decision statement as both true and false.

Example: Consider a function that determines eligibility based on multiple conditions:

def is_eligible(age, residency_years):
    return age > 18 and residency_years >= 5

Condition coverage would involve testing combinations where each condition (age > 18 and residency_years >= 5) evaluates to both true and false.

3. Loop Coverage

Testers use Loop Coverage to test the correctness and behavior of loops within the code. Testers ensure they test loops for zero iterations, one iteration, multiple iterations, and boundary conditions.

Example: Consider a loop that sums numbers up to a specified limit:

def sum_to_limit(limit):
    sum = 0
    for i in range(1, limit + 1):
        sum += i
    return sum

Loop coverage would test this function with limit values of 0 (zero iterations), 1 (one iteration), a moderate number (multiple iterations), and a high number near the boundary conditions.

4. MC/DC (Modified Condition/Decision Coverage)

Modified Condition/Decision Coverage (MC/DC) ensures that each condition within a decision statement independently affects the outcome. This technique is especially valuable for high-integrity systems where a high confidence level in the software's behavior is essential.

Example: Consider a function with a complex decision:

def process_application(age, income, credit_score):
    if age > 18 and (income > 30000 or credit_score > 600):
        return 'Approved'
    else:
        return 'Denied'

Testers use MC/DC test scenarios in which altering a condition changes the decision's outcome, ensuring independent testing of each condition's impact on the decision.

Tools and Technologies Used for Dynamic White Box Testing?

Several tools and technologies are commonly used to conduct Dynamic White Box Testing, as follows:

1. Akto

Akto is a proactive API security platform with a vast library of tests covering the OWASP Top 10, such as authentication, SSRF, XSS, and security configurations. This extensive testing library is crucial for dynamic white box testing, as it involves running the code and checking its behavior in various scenarios.

2. Testsigma

Testsigma is an AI-powered continuous testing platform that supports dynamic white box testing. It enables users to create automated tests that can execute against web applications, mobile apps, and APIs. Testsigma supports various testing types, including functional, regression, performance, and security, making it versatile for dynamic white box testing needs.

3. Selenium

Widely recognized for automating browsers across different platforms, Selenium is a popular choice for dynamic white box testing. Selenium supports multiple programming languages such as Java, C#, Python, Ruby, and JavaScript, facilitating the automation of complex UI interactions and workflows. Selenium is particularly useful for testing web applications' functionality and user interface.

4. Appium

Appium is another tool that supports dynamic white box testing. It is specifically designed for mobile app testing and allows for automating native, hybrid, and web applications on iOS and Android devices. Appium's support for cross-platform testing makes it a powerful tool for ensuring the robustness and reliability of mobile applications.

Final Thoughts

Dynamic White Box Testing is a powerful approach for evaluating the internal workings of applications during runtime. It provides critical insights into code execution and reveals hidden errors that static analysis might miss.

This methodology enhances code quality by thoroughly testing internal paths, verifying code coverage, and optimizing performance. By dynamically testing the software, developers can ensure that the application behaves correctly in real-world conditions, leading to more robust and reliable software.

Integrating advanced tools like Akto into your testing strategy further amplifies the benefits of Dynamic White Box Testing. As a proactive API security platform, Akto offers extensive tests covering OWASP's Top 10 vulnerabilities, aiding in identifying and mitigating security risks during code execution. Utilizing such tools ensures comprehensive dynamic testing, addressing the application's functional and security aspects and ultimately leading to higher-quality, secure software solutions.