Black Box Testing

Black Box Testing refers to testing without knowledge of the internal workings of the system being tested. For example, when black box testing is applied to software engineering, the tester would only know the “legal” inputs and what the expected outputs should be, but not how the program actually arrives at those outputs.

Black box testing is also known as behavioral Testing since only the external behaviors of the program are evaluated and analyzed.

Only input for test engineer in this type of testing is requirement document and functionality of system which you get by working with the system.

Purpose of black box testing is to

* Make sure that system is working in accordance with the system requirement.

* Make sure that system is meeting user expectation.

The following are the most famous/frequently used Black Box Testing Techniques/Types.

* Equivalence Partitioning:- Equivalence partitioning is a black box testing method that divides the input domain of a pprogram into classes of data from which test cases can be derived. EP can be defined according to the following guidelines:

o If an input condition specifies a range, one valid and one two invalid classes are defined.

o If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.

o If an input condition specifies a member of a set, one valid and one invalid equivalence class are defined.

o If an input condition is Boolean, one valid and one invalid class are defined.

* Boundary Value Analysis:- Boundary Valve Analysis (BVA) is a test case design technique that complements equivalence partitioning. Rather than selecting any element of an equivalence class, BVA leads to the selection of test cases at the “edges” of the class. Rather than focusing solely on input conditions, BVA derives test cases from the output domain as well.Guidelines for BVA are similar in many respects to those provided for equivalence partitioning.

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