Updated June 9, 2023
Difference Between White Box Testing and Black Box Testing
One of the most important stages of the software development lifecycle is a quality assurance or software testing, and it is a huge field. There are two widely employed methods of Software testing, i.e. White Box testing and Black Box testing. Let’s see the brief definition for now, and then we can proceed with the detailed difference and understanding of White Box testing vs Black Box testing.
- White Box Testing: This is an approach to test even the product’s internal functions and see what’s happening with the data before generating the output.
- Black Box Testing: This is an approach to test the product in a way that says if it gives the desired output or not.
Comparison – Infographics
Below are the top 11 differences between White Box testing and Black Box testing.
Key Differences Between White Box Testing vs Black Box Testing
Let us discuss some of the major differences between White Box testing and Black Box testing:
White Box Testing
White box testing is also called as open box testing, transparent testing or internal testing. This tests every aspect of the software, and the tester needs programming abilities along with the complete design of the software that he is testing. The major objective of this testing approach is to study the whole internal structure of the software product and see if the data consumption, processing, and output generation is happening right and as per the design.
White box testing is useful for:
- To spot incorrect syntax.
- To identify the logical error and design errors.
Advantages:
- White box testing helps to optimize the source code.
- All the workflows will be covered.
- As the testers of white box testing will have a programming background, it will be easy to identify the logical errors and inappropriate code segments.
Disadvantages:
- White box testing requires the testers to be skilled in programming and build test suites that can be used for running regressions, etc.
- The computation resources that the white box testing might employ may be expensive.
- There is still scope for missing out on the hidden errors in the logic implemented.
- The tester might have to develop their own frameworks, and no external tools might help to do full-fledged testing independently.
Black Box Testing:
Black box testing is also called external testing, closed testing, and behavioral testing. This testing’s approach is very clear by the name itself that the tester will simply test the outputs for the corresponding inputs without any knowledge about the source code.
Black testing is useful for:
- To verify the errors in the external dependent source codes and data (like external databases).
- Optimizing the interface errors. For checking missing or erroneous functions.
- Finding the input errors and access errors.
Advantages:
- The more efficient way of testing large code segments.
- No need for a technical background or technical proficiency.
- The design of test cases is easy.
- Black box testing can be automated very easily.
Disadvantages:
- An only a limited number of inputs can be tested.
- It is difficult to design the test cases if the tester does not have knowledge of the software specification.
- There is limited coverage of the application, and hence the testing cannot be exhaustively done on all components.
Comparison Table
Let us discuss the topmost differences between Black Box testing and White Box testing.
| Black Box testing | White Box testing |
| It is a way of software testing where the internals of the software is never exposed. | It is a way of software testing where the internals of the software is exposed to the test environment. |
| This is mostly like testing if the software is working fine and if the software is giving the expected output. | This is mostly like testing if the software is working by consuming the data in the way it is supposed to do. |
| This can be carried out even by a non-technical person. | This test is carried out by a software test engineer and also by software developers. |
| The Black Box tester need not have knowledge of the implementation. He just needs to know what must be the output for the corresponding input. | The White Box tester needs to have the knowledge of implementation because he needs to check the internals of the code. |
| This can also be referred to as ‘External Software testing’ and ‘Closed testing.’ | This can also be referred to as ‘Internal Software testing’ and ‘open testing’. |
| The functionality of the software is tested in this. | The structure and operations are tested in this form. |
| The design for Black Box testing can be carved out of the requirements specifications. | The design for White Box testing can be carved out of the detailed software design document. |
| This consumes less time. | This takes more time. |
| This is not suitable for algorithm testing. | This is the preferred one for algorithm testing. |
| For example – if ‘a’ is input, is ‘b’ the output? | For example – if ‘a’ is the input, then is it consumed by function b() to return the right value ‘c’? |
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Conclusion
Well, both White Box testing and Black Box testing have their advantages and disadvantages. Employing one kind of testing approach, you will not be able to achieve quality assurance. This is why it is wise, and also, it is recommended to employ both while validating and verifying the software product for being bug-free. There is also something called Grey Box testing which is a combination of both white box testing and black-box testing, but I will leave it to you as an exercise to explore yourself.
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