Black Box testing

Tools Used

Black box testing tools are mainly record and playback tools. These tools are used for regression testing that to check whether new build has created any bug in previous working application functionality. These record and playback tools records test cases in the form of some scripts like TSL, VB script, Java script, Perl.

Definition

Black box testing treats the system as a "black-box", so it doesn't explicitly use Knowledge of the internal structure or code. Main focus in black box testing is on functionality of the system as a whole. The term 'behavioral testing' is also used for black box testing

comparison testing

Different independent versions of same software are used to compare to each other for testing in this method.

Methods of BBT : Graph Based Testing Methods:

Each and every application is build up of some objects. All such objects are identified and graph is prepared. From this object graph each object relationship is identified and test cases written accordingly to discover the errors.

Equivalence partitioning

Equivalence partitioning is a black box testing method that divides the input domain of a program into classes of data from which test cases can be derived. Test both sides of each boundary Look at output boundaries for test cases too Test min, min-1, max, max+1, typical values

Equivalence partitioning techniques

How is this partitioning performed while testing: 1. If an input condition specifies a range, one valid and one two invalid classes are defined. 2. If an input condition requires a specific value, one valid and two invalid equivalence classes are defined. 3. If an input condition specifies a member of a set, one valid and one invalid equivalence class is defined. 4. If an input condition is Boolean, one valid and one invalid class is defined.

Boundary Value Analysis:

Many systems have tendency to fail on boundary. So testing boundry values of application is important. Boundary Value Analysis (BVA) is a test Functional Testing technique where the extreme boundary values are chosen. Boundary values include maximum, minimum, just inside/outside boundaries, typical values, and error values.

Disadvantages of black Box testing

The test inputs needs to be from large sample space. - It is difficult to identify all possible inputs in limited testing time. So writing test cases is slow and difficult - Chances of having unidentified paths during this testing

Error Guessing:

This is purely based on previous experience and judgment of tester. Error Guessing is the art of guessing where errors can be hidden. For this technique there are no specific tools, writing the test cases that cover all the application paths.

Advantages of Black Box testing

- Tester can be non-technical. - Used to verify contradictions in actual system and the specifications. - Test cases can be designed as soon as the functional specifications are complete

BVA techniques

1. Number of variables For n variables: BVA yields 4n + 1 test cases. 2. Kinds of ranges Generalizing ranges depends on the nature or type of variables Advantages of Boundary Value Analysis 1. Robustness Testing - Boundary Value Analysis plus values that go beyond the limits 2. Min - 1, Min, Min +1, Nom, Max -1, Max, Max +1 3. Forces attention to exception handling