Blackbox vs Whitebox Testing: What are the Key Differences?

Quick Summary: When it comes to application security testing, Blackbox testing and Whitebox testing are two crucial approaches. How are they different and which one is more important? This blog provides a detailed comparison to help answer these questions and more. Keep reading for essential information to distinguish between these two security testing methods.

The world’s most renowned chain of coffeehouses, Starbucks lost millions of dollars when its POS (Point-of-Sale) system ceased operating in 2015. This incident occurred due to a system refresh fault stemming from a software glitch. Had the company tested its POS software, this incident could have been avoided.

What can companies learn from the above event? Obviously, it shows the significance of software testing. Software applications can fail, and testing is a way to avoid the risk by removing potential bugs and errors. When it comes to testing two methods are used, Blackbox and Whitebox testing.

Black-box testing is a method in which testers evaluate a software application without caring about the interior. Whereas the White box is a testing method in which testers work on the source code to detect bugs. The distinctive approach of each of these testing methods makes it hard to make a choice.

It is critical to pick the right testing methodology to ensure impeccable functionality, performance, and quality of software applications. However, the dilemma of Whitebox vs Blackbox testing can make it hard to reach a conclusion. So, in this blog, we are going to discuss the differences between black box and white box testing and find a solution to the dilemma.

Let’s brush up on your knowledge and clear up any doubts.

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An Overview of Blackbox vs Whitebox Testing

Blackbox is a kind of testing method where the tester doesn’t know the internal structure, design, or implementation of the software application being tested. It evaluates the external functionality and behavior of a software application. The tester provides inputs and observes the responses or output to assess whether the software application is functioning as per expectations or not.

On the other hand, Whitebox is a kind of testing method where the tester is aware of the internal implementation or design of a software application. The tester evaluates the design, structure, coding, and implementation of software applications. It helps to find bugs and errors inside application code and design.

We can say Blackbox testing tracks software application issues from outside, while the Whitebox method looks inside your application to find issues.

White Box vs Black Box Testing: A Detailed Comparison

The following points describe the differences between white box and black box testing based on three factors.

Process

Blackbox is a rigorous and comprehensive approach to application testing. It aims to perform testing from the end-user's perspective. The process of Blackbox testing starts with the testing team understanding the specification document for software applications.

There are various testing techniques such as boundary-value analysis and equivalence partitioning used to determine valid inputs and possible outputs. Test cases are built based on this information and run to check their success. After this, the actual outcomes and expected outcomes are compared to find failed tests that are flagged as bugs.

The tester will report the bugs to developers who will fix them. After fixing the problems, there will be a retest to check if the bugs are fixed.

Whitebox testing on the other hand is ‘surgical’ in nature and begins by understanding the internal fabric of a software application. However, this is a more effective method for smaller targets. The objective of this method is to evaluate all possible scenarios and cases for the target. Here target can be a component, application, or feature.

The process of white box testing starts by identifying the target. Testers usually choose the smallest possible logical unit as the target to ensure flawless functionality. They move to the next unit and so on. A flow graph is created mentioning all possible scenarios.

The scope of testing is defined, and test cases are created accordingly. After creating the flow chart, the tester will map the path for testing and frame it as test cases. The next comes the execution phase to run tests and record bugs.

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Testing Techniques

There are different types of techniques for software application testing. Testers use these techniques to evaluate different aspects of applications. Whitebox testing is more granular and focuses on in-depth analysis. So, the testing techniques are aligned to meet those objectives. On the flip side, black box testing aims to assess application behavior without touching the internal structure. So, the testing techniques analyze applications based on input-output actions.

The following are the techniques used in the black box testing method:

• Boundary-Value Analysis: The tester focuses on boundary values of the range of valid and invalid inputs in this case. It relies on the premise that there is a high chance of errors when testing near the boundary.
• Equivalence Partitioning: In this approach, input data for testing is split into valid and invalid values. Also, it is necessary that the partitions created after splitting the inputs must exhibit the same behavior.
• Decision Table Testing: Under this Blackbox testing technique, different combinations of input conditions are used that yield various outcomes. This is a good approach to finding the best test cases for applications with complex business logic.
• Experience-based Testing: This type of technique is based on intuition, knowledge, and understanding that comes from a tester’s experience. A tester guessing the potential errors is the right example of this technique.
• Comparison Testing: It is based on the comparison of a current software application with an already existing application. This comparison helps evaluate the weaknesses and strengths of current software applications vis-a-vis the existing solution. It helps to build solutions with improved functionality.
• Graph-based Testing: A technique that creates an ‘object graph’ by identifying objects in a software application. The graph helps to find relationships between objects and create test cases.

The following are the techniques used in the white box testing method:

• Branch Coverage: This technique covers all the decision nodes in conditional flows. As a result, it checks all the outcomes of every condition in various decision points at least once. It ensures the execution of every branch in all decision points.
• Control Flow Testing: This Whitebox testing technique decides the sequence in which a control structure executes the instructions of an application.
• Statement Coverage: This kind of testing technique includes executing all statements of the source code at least once. It allows testers to analyze source code against the set expectations.
• Condition Coverage: Tester evaluates all conditions for various possible outcomes in this technique.
• Path Coverage: In this testing program paths are tested, and it is useful for testing complex programs.

Approach

There are different goals when it comes to white box vs black box testing. The main objective of black box testing is to ensure the flawless functioning of software applications for the end users. Further, the tester assumes the external behavior of the application and doesn’t bother to consider the internal workings.

The Black box approach is well-suited for greater levels of testing that includes acceptance and system testing. There is no need for a tester to have in-depth programming skills in this method. Further, this testing approach is hard to automate. In this method, testers build test cases based on specification documents.

Since this testing method involves testing software applications from outside, it doesn’t access the source code. As a result, it fails to test application algorithms. It doesn’t require testing skills and a tester with lower skills can also perform it.

White box testing is rather comprehensive and tedious because it involves analyzing the source code and application behavior from the inside. The main objective of White testing is to ensure the quality and integrity of code.

Since a tester has an in-depth understanding of the inner workings of an application, it enables them to evaluate every aspect of the code. This testing approach is suitable for the lower levels of testing like integration and unit testing.

Whitebox testing requires a good grasp of programming skills to create effective test cases. Further, it is quite easy to automate. Testers use detailed design documents to build test cases. This testing method is more granular and provides in-depth analysis.

It is also useful for testing algorithms. However, Whitebox testing is also resource-intensive and attracts more costs. Since testers can access the source code, they can remove unnecessary lines. But there is also a potential risk with exposed source code in the case of outsourcing testing.

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Ending Notes on Whitebox vs Blackbox Testing

Testing is crucial to assess their quality and make them bug-free before their launch. Whitebox and Blackbox testing offer their own pros and cons. Both testing approaches can guarantee you the best versions of software applications. Blackbox testing checks the behavioral aspects and Whitebox testing checks the structural aspects.

Both testing approaches work for different needs. White-box testing is used in lower levels of testing and performed by developers. Black-box testing is used in higher levels of testing and performed by a quality assurance team. If you want to test your applications or APIs with blackbox testing method, you can leverage ZeroThreat as your go-to platform.

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