Methods of black box testing - Graph based testing methods and Equivalence Partitioning

Black Box Testing is testing without knowledge of the internal workings of the item being tested. There are four black box testing methods:

Graph-based Testing Methods
Basic idea: A "cause" is an input condition, and an "effect" is a specific sequence of computations to be performed. A cause-effect graph is basically a directed graph that describes the logical combinations of causes and their relationship to the effects to be produced.
- Black-box methods based on the nature of the relationships (links) among the program objects (nodes), test cases are designed to traverse the entire graph.
- A graph is created between the objects and the relationships.
- From the graph, each object relationship is identified and test cases written accordingly to discover the errors.

Equivalence Partitioning
This method divides the input domain of a program into classes of data from which test cases can be derived. It reduces the number of test cases. The guidelines of Equivalence Partitioning are :
- If an input condition specifies a range, one valid and two invalid equivalence classes are defined.
- If an input condition requires a specific value, then one valid and two invalid equivalence classes are defined.
- If an input condition specifies a member of a set, then one valid and one invalid equivalence class are defined.
- If an input condition is boolean, then one valid and one invalid equivalence class are defined.