Difference Between Black-Box Testing And White-Box Testing

The development of software is the result of the desire to meet certain requirements of the customers and the stakeholders. These requirements are satisfied with the help of writing programs. These programs or code give objects the functionality they are intended to perform. So, once the development process is done, it is necessary to test whether all the functionality is covered in the development process or not and each of them is working exactly the way it should. It is called as Black-Box testing.

Along with that, it should also be tested that the code is executing as desired and in an efficient way. It is called White-Box testing. Black-box testing and White-box testing are the two kinds of software testing which covers a major part of the testing need. In this article, we will discuss ‘what is Blackbox testing and White-box testing?’ and ‘what makes them different from each other?’.

Black-Box Testing

Black-Box testing involves looking for the defects in the functionalities of the software without caring about ‘how the program has been written and what is the algorithm followed?’.

Difference Between Black-Box Testing And White-Box Testing
Image Source: Webomates

It just checks, whether the software can meet the requirements it is developed to or not? Because it doesn’t matter how the software is developed if it’s not good enough to satisfy the needs of the customers and stakeholders.

A functionality is chosen by the tester and then different inputs including the boundary conditions are given to the software and then the generated output is compared with the correct output. If they come out to be the same then the functionality is passed else fails.

The tester tries to put each requirement to test. He doesn’t need to have any programming knowledge.

Black-Box Testing Techniques

1. Decision Table

Various input combinations are provided to the system and their corresponding response is noted in a tabular form for further analysis.

2. Boundary Value Test

The functionalities are tested on the boundary value inputs which are the upper and lower limits of a variable.

3. Equivalence Partitioning

In this technique, the input values are partitioned as valid or invalid input and the system is expected to have equal behaviour with both of them.

4. Error Guessing

The tester uses his experience to find potential errors by exploring the software.

5. Cause Effect Test

It checks the consistency of the result by varying the conditions that can affect it. 

White Box Testing

White Box testing is also known as structural testing, open-box testing, glass box testing, clear-box testing and transparent box testing because the tester is allowed to see through the outer shell to the internal architecture of the software.

Difference Between Black-Box Testing And White-Box Testing
Image Source: WordPress.com

It tests the internal code and infrastructure of the software under test. This testing is performed by using predefined inputs and then comparing the expected output with the actual output.

Test cases are designed by the testers who have enough programming knowledge and experience necessary for effective testing. A tester with no programming knowledge is not eligible for this testing.

These test cases find defects in the internal operation of the application. It checks whether the flow of input and output is undergoing smoothly through the software and it is free from any potential security threat or not. The creation of test cases is based on the document generated during the design phase of the software.

White-Box Testing Techniques 

1. Data Flow Testing

This testing technique checks whether the flow of data stored in the variables is going perfectly and the data is following through the correct path for generating the desired output.

2. Control Flow Testing

It involves testing the sequence of execution of the statements and instructions. For software to work in the desired way, the program statements must execute in the correct sequence.

Difference Between Black-Box Testing And White-Box Testing
Image Source: GeeksforGeeks

3. Branch Testing

The design phase in the software development life cycle involves the creation of a control flow graph which includes some branches, so it is important to test that the code can execute those branch conditions.

4. Statement Testing

This testing is done to execute each statement for at least one time. It ensures that each statement is properly written and will not lead to an obstacle in the operations of the software.

5. Decision Testing

This technique is used to test all the decision making statements like for loop, while loop, do-while loop, if-else and switch-case statements. It ensures that the code can execute both the possible outcomes even if the condition is true or false.

black-box testing

Image Source: Professional QA

Black-Box Testing vs Whitebox Testing

Black-Box TestingWhite-Box Testing
This kind of testing can be done by a tester without any knowledge about the internal structure of the software.This type of testing requires the tester to know the internal structure of the software.
It is also known as the Behavioural/Specification-based testing and input-output testing.It is also known as structural testing, clear-box testing, code-based testing, glass-box testing.
Black-Box testing is done in the higher stage of testing, generally during system and acceptance testing.Unit testing, integrating testing are the types of white-box testing, carried out at the lower level of testing.
The tester doesn’t need to have any programming knowledge for undertaking the test.The tester must have the programming knowledge for undertaking the test.
The tester does not need to have any knowledge about the implementation of the software.The tester should have complete insight into the implementation of the software.
Black-Box Testing is not completely automated.White-Box testing is generally automated.
The main focus of the test is on the functionalities of the software.The main focus of the test is on the code quality of the software.
It can be started once the requirements and specifications of the software are documented.It can be started once the design architecture of the software is documented.
It can be performed by developers, end-user, tester.It can only be performed by the tester, developers, who understands the software program.
It is not required to give testers access to the source code.It is required to give testers access to the source code.
Equivalence partitioning, boundary value analysis are used for black-box testing.It uses the statement coverage, branch coverage and path coverage techniques.
It finds out the missing and incorrectly implemented functionalities defect.It finds out the errors in the logic and design of the software.
Black-box testing costs less than white-box testing.It cost more than Black-Box testing.