Black Box Testing Techniques
Overview
In this tutorial, we will learn different types of Black Box Testing Techniques. In Black box testing the QA Team doesn’t know the internal working and implementation of the application under test.
Black-box test cases are designed from an examination of the input/output values and no internal knowledge of source code is required. The testing team knows the test inputs to the application and the expected outcomes of the tests. Most of the manual functional testing is black-box testing.
Black Box Testing Techniques
Some of the important Black Box Testing Techniques are as follows:
- Error Guessing
- Boundary Value Analysis(BVA)
- Equivalence Class Partitioning(ECP)
- Comparison Testing
- All Pairs Testing
- Decision Table Testing
- Fuzzy Testing
- State Transition Testing
- Risk-based Testing
- Graph-based Testing
- Orthogonal Array Testing
- Use Case Testing
Equivalence Class Partitioning
In the Equivalence Class Partitioning approach, the domain of test input values to a software application is partitioned into a set of equivalence classes. This partitioning is done such that the behavior of the application under test(AUT) is similar for every input data belonging to the same equivalence class.
The main idea behind defining the equivalence classes is that testing the code with any value belonging to an equivalence class is as good as testing the application with any other value belonging to that equivalence class partition.
For Example, consider an input field that allows an input integer for the student’s age. We can assume values in the range of 0 to 100 for the age data field. The three equivalence classes are as follows:
- Set of negative integers as the age
- Set of integers in the range of 0 to 100 as valid age
- Set of integers larger than 100
The test cases must include representatives for each of the three equivalence classes. The input data values to a system can be specified by a range of values, then one valid and two invalid equivalence classes should be defined. The possible equivalence class test cases can be: {-5,15,200}
Boundary Value Analysis
Boundary value analysis is the selection of test cases at the boundaries of the different equivalence classes. The idea is that programming error frequently occurs at the boundaries of different equivalence classes of inputs. Programmers often fail to see the special processing required by the input values that lie at the boundary of the different equivalence classes. For example, programmers may improperly use < instead of <=, etc.
For the above example, which takes the student’s age as integer values in the range of 0 and 100, the boundary value test cases are : {0, -1,100,101}.
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