Black Box vs White Box: Difference and Comparison

The testing of software is always an important part of the development of the software life cycle, be it web-based or mobile application software.

Testing a software not only confirms the quality of the software but also provides the developer with a chance to improve if the software has faults.

Almost all the software applications need some coding and for the code to run smoothly, they have to go through some tests. For evaluating the functionality and quality of the codes, testers perform black box and white box tests.

Key Takeaways

1. Black box testing is a software testing method that focuses on the functionality of an application without knowledge of its internal structure. In contrast, white box testing involves testing an application’s internal logic and structure.
2. Black box testing is performed by testers who don’t necessarily have programming knowledge, while white box testing requires an understanding of the application’s code.
3. White box testing allows for more thorough and targeted testing, while black box testing focuses on user experience and functionality.

Black Box vs White Box

Black box testing is a software testing methodology in which the tester analyzes the functionality of an application by only considering the system’s external behavior. In white box testing, the tester also considers the internal functioning of the application and analyzes it during testing.

Black Box testing examines the functions of the application according to its specifications, due to which sometimes it is also known as specification-based testing.

Though black box testing can be performed at any stage of the software development, the testing team most of the time performs it during the software life cycle testing.

White box testing, as the name suggests, is the testing where it checks the inner structure of the application against its functions, and the tester in charge can see through the outer box or shell.

For designing the test cases in this method of testing, the internal perspective and programming languages of the system are used.

Comparison Table

Parameters of Comparison	Black Box	White Box
Skills required for testing	A tester should have experience in testing.	A tester should have the proper knowledge and understanding of programming languages and coding.
Report	It detects the faults in the features and performance of the software.	It detects the faults in the product and codes.
Level	Black Box testing is high-level testing.	White Box testing is low-level testing.
Algorithm test	Black Box testing is not the best for algorithm tests.	White Box testing is best for algorithm tests.
Programming knowledge	The knowledge of programming is not required.	The knowledge of programming is required.

What is Black Box?

Black box testing helps in checking the functions of a software application without knowing the inner details of the application.

This type of testing mainly concentrates on the input and output of the software application and is only based on the software instructions, requirements, and specifications.

Oftentimes, this type is testing is also named specification-based testing as it tests the functions according to the specifications stated.

It is also capable of testing the applications of companies like Google and Windows without knowing how the codes are implemented in their applications, by just evaluating the inputs and outputs.

The steps required for carrying out any type of Black Box testing are as follows:

• The Initial step is to examine the requirements and specifications of the system.
• The tester In charge selects the correct input for checking if the SUT processes them accurately. Also, some incorrect inputs are selected to check whether the SUT can detect them or not. 
• The expected outputs are being stated by the tester for all the inputs.
• The tester builds the test cases with the Inputs that are selected.
• The test cases are performed.
• The actual outputs are compared with the expected outputs by the tester.
• If defects are found, they are fixed and tested again.

What is White Box?

White Box testing is the technique used for testing the software in which the internal structures, details, etc are tested to examine the flow of input and output and for improving the design, security, and usefulness of the software.

The codes in the white box testing are not covered or hidden in the box and can be seen by the tester in charge, due to which this method of testing is also named Glass box testing or clear box testing.

It was termed white box testing because of the see-through concept used in it. The name itself symbolizes the ability to see through the box or the outer shell of the software. The software codes that are tested by the white box testing are as follows:

• Holes in the internal security.
• Faulty structured paths in the process of coding.
• Specific input flow through the code.
• Expected output.

White Box testing can be done on different levels of software development. The sole purpose of conducting this test is to check the status of the working flow of the software application.

It tests the series of the pre-set inputs in opposition to the expected outputs to detect a bug if the specified input does not match the expected output. Before performing the white box testing, the tester should be aware of the code of the application.

Since it examines the quality of the inner workings of the application, the tester must know the programming languages that are required for testing.

After that, the tester should create test cases and perform them. One way for creating cases is by writing codes and the other way includes Manual testing, error testing, trial, etc.

Main Differences Between Black Box and White Box

1. Black box testing requires less time to give any result, whereas white box testing needs more time for giving results as compared to black-box testing.
2. Having programming knowledge to conduct black-box testing is not required, whereas the knowledge of programming is required for white box testing.
3. Black box testing is mainly performed by the testing team, whereas white box testing is performed by the developers of the software.
4. Black Box testing is considered high-level testing as the tester does not have information about the software’s inner details, whereas white box testing is considered low-level testing because the tester has the understanding of programming languages required in the software application.
5. The tester in charge of performing black box testing should have experience in testing software, whereas the tester that performs white box testing should have programming knowledge.

References

1. https://ieeexplore.ieee.org/abstract/document/7886931/
2. https://dl.acm.org/doi/abs/10.5555/202699