Black-box Testing is a software testing technique performed usually without the knowledge of internal coding OR the structure of the Application Under Test (AUT). Black-box testing is also known as Behavioral Testing and these tests are both Functional and Non-Functional. We can use Black-box Testing Techniques in the following test levels.

Unit Testing

Integration Testing

System Testing

Acceptance Testing

Black-Box Testing Techniques

This type of testing is usually performed by the QA Team. The following Techniques are used by the testers to design the test cases.

Error Guessing

Boundary Value Analysis

Equivalence Partitioning

Decision Table Testing

State Transition Testing

Graph-based Testing

Comparison Testing

Error Guessing:  

Error Guessing is an intuitive and also an ad-hoc test case design technique based on the tester’s experience, intuition, previous defects, etc.,

So, we design the test cases, based on the tester’s experience and thinking capability i.e the tester should guess the scenarios that the developer might miss in the coding part.

Error Guessing has no specific rules. But, there is a possibility to uncover some major defects which we may miss during the formal testing process.


Here is an example of Error Guessing.

Suppose, we have to validate a newly added text box in the application screen.

Here, the requirement specification is “The text box should accept only two-digit numeric values.”

The tester can come up with the following test cases based on the Error Guessing Black-box Testing Technique.

In the above example, the tester is validating the field in all possible ways, to ensure that they have inserted the text box field properly, based on the specification.

Here, the tester does not have any idea about the back-end coding part, but, still, he is able to verify the code by entering different combinations of the input data, thereby assuring a proper validation of the given requirement.

Please follow our blog to see the other black box testing techniques with a detailed explanation as well as examples.