Gray Box Testing: When Black and White Don’t Suffice

Quality assurance (QA) teams use different testing approaches and their combinations in software testing. Thus, they often combine the white box and black box testing practices into gray box testing. This approach allows engineers to assess the platform from different angles without investing many resources. It takes the best from two testing types and offers a comprehensive solution for discovering software flaws and vulnerabilities.

Let’s see why gray box testing can be beneficial and what its fundamentals are.

What Is Gray Box Testing?

Gray box testing, also spelled grey box testing, is a combination of black box and white box testing. In the first method, testers have no knowledge of the internal application structure and no access to its source code. The second approach, on the contrary, gives all the internal information, including structure, code, and processes.

Gray box testing merges those two methods. As a result, QA specialists have a partial understanding of and access to the internal processes. This opens an opportunity to prevent more issues than when using the white box or black box approaches separately.

Gray Box Testing Advantages

The concept of gray box testing is that it embraces the best features of both black box and white box testing. Here they are:

• Better test coverage. The procedure requires platform examination from both sides: developers and users. If, usually, in the black box vs. whitebox testing case testers need to work either checking how the platform responds or what is inside, there is no such compromise in gray testing. Thus, there are more chances to catch the bug and then fix it.

• No programming experience needed. Testers don’t need programming experience to conduct software assessments. They have access to system components and internal documentation, and even that will be enough to successfully achieve the desired result.
• Unbiased approach. Since QA engineers have partial access to the internal system and act as end-users, they can discover more issues that wouldn’t be visible if they had extensive knowledge about the software’s background.
• Non-intrusive procedure. In gray box testing, QA teams are not required to gain full access to the source code. Thus, in terms of security, it is beneficial as you don’t have to share access or sensitive data.
• Time efficiency. This type of testing takes less time for procedure execution, leaving more time and resources for defect fixing.

Gray Box Testing: Real Case Scenario and Best Situations to Apply It

The main goal of gray box testing is to improve software quality by checking its functional and non-functional aspects. An example of gray box testing is investigating why an error occurs when clicking on a link.

During this scenario, the testers will both check the link imitating the user and look at the internal system, which is the error code table. If the QA team used a particular method, for instance, black box testing, they would just see that the issue indeed persists when clicking on the link. However, they would not be able to explore what might be causing it.

Gray box testing is best suited for the following scenarios:

1. 1. Integration testing. In software engineering, gray box testing can help integrate different software components. Individually, they can perform well, but when used together, they can be incompatible. Since the problem can be hidden outside or inside, gray box testing can cover both sides.
2. 2. Security testing. This testing method can cover various aspects of application security and vulnerability. Gray box testing can detect employees’ fraud actions from the inside and research attackers’ malicious intent from the outside. For example, in cross-site scripting, XSS testing can be applied to situations where hackers gain control over user data and actions.
3. 3. Usability testing with technical knowledge. On top of researching the user’s part, which is easy to use in usability testing, gray box testing can go deeper and, with a technical background, investigate database structure.

Difference Between White Box, Black Box, and Gray Box Testing

As gray box testing combines the experience of black box and white box testing, it comes with many advantages compared to these two techniques.

Gray Box Testing Advantages Over Black Box Testing

Unlike black box software assessment, the gray box allows testers partial access to the internal system and documentation. Thus, based on that information, the QA engineers can build more comprehensive test suits that target specific features of the application.

Gray Box Testing Advantages Over White Box Testing

When testing with white box testing methods, the focus is gathered only on the internal systems, leaving the user’s impact behind. In the case of gray box testing, these two aspects are merged. Moreover, it is not required to dive deep into the source code structure, which requires time and exceptional expertise in coding.

Gray Box Testing Techniques

Gray box testing provides limitless opportunities that help the developer’s team ensure the product runs as intended. Precisely, with the help of special techniques, testers can create penetration testing that can check the internal system for its ability to resist malicious attacks or some interior threats. Since this testing method is considered a middle ground between the white and black testing methods, it can combine their methods as well. In the section below, we have collected the most effective techniques for implying gray box testing.

Employment of the Available Information

The first bunch of methods have been combined in this section for a specific reason. The first group of techniques involves the use of the data that is already available in the project. So, what does the basis of gray box testing hide in its integral processes?

• Using the SSD documentation. The first step in successfully implementing gray box testing is a thorough understanding of the SSD or system design document. Without a global understanding of the internal system and global architecture of the project, it will not be possible to run the tests successfully.
• API documentation. The functions and limitations of the available API components should be accessible in the project documentation as well. It would simplify the testing process and provide an understanding of the initial project’s components.
• User story testing and requirements. This component is extremely important for the testing period since it provides the developer’s team with a concise understanding of the user’s demands and checks it during the testing routine.

Basic Techniques of Gray Box Testing

Since the specifics of gray testing don’t imply the creation of test cases but the use of evaluation algorithms, it’s worth noting the specific techniques used for this process.

• Boundary value analysis. This technique is necessary to check the minimum and maximum allowable values of the testing data. It’s one of the most important methods in gray box testing since it allows the testers to identify errors on the edge of acceptable values.
• Equivalence partitioning. This specific strategy implies the dividing of the input data into specific groups, which improves the efficiency levels of the testing routine by eliminating the test scenarios that provide identical test results. Originally, this testing method was actively used in the black box testing routines, but can also be implied during the gray box tests as well.
• Use of the decision tables. Decision tables are testing tools that help the developer team create test scenarios based on the initial data. The fact is that a competent decision table can greatly facilitate the testing process and receiving the desired results as well.
• Checking the states’ transitions. During this process, the tester will have to go through all possible combinations of actions multiplied by the product’s states. In simple words, the specialist will artificially create the states to identify possible errors during the transitions of the product states.

Gray Box Testing Process

The exploration of the gray box testing routine is a process that is based on multiple simple but crucial factors. In this section, we have defined the main steps that will help any testing team improve their skills in the gray box testing routine.

Importance of Communication

Communication is an irreplaceable skill that can increase the efficiency of your teamwork several times at once. To achieve such results in the testing routine, it’s necessary to establish proper communication between the developers, testers, and stakeholders. This simple step will help avoid miscommunication and set clear goals for each member of the team.

Balance In Knowledge and Objectivity

Prejudice in the testing routine should be avoided. In the case of gray box testing, it’s essential to ensure a balance between existing knowledge about the project and critical thinking. Some companies may even hire outsourcing specialists to receive unbiased opinions regarding the project.

Proper Documentation Management

By checking the proper testing documentation, any professional specialist can get to the heart of the problem from the very first lines. Therefore, it’s vital to keep the proper documentation records that the projects oblige you with. This step will not only help you keep the project in order but also track the significant changes through the testing routine.

Conclusion

Gray box testing is an irreplaceable tool for any complex development process. This method’s main feature is that it gathers the best techniques of both white and black box testing routines, which helps to cover a wider area of the product’s layers. Gray box testing offers a wide range of software exploration methods, both within and outside the company. Its techniques focus on both the users’ side and the internal system structure. Therefore, in combination with proper testing methods, it makes gray box testing a golden means for any QA team.