Equivalence partitioning - TwoGears/hakomo-guides GitHub Wiki

Equivalence partitioning (EP) is a specification-based or black-box technique. It can be applied at any level of testing and is often a good technique to use first. It is a software testing technique that divides the input test data of the application under test into each partition at least once of equivalent data from which test cases can be derived.An advantage of this approach is it reduces the time required for performing testing of a software due to less number of test cases.
Example:
Assume that the application accepts an integer in the range 100 to 999 Valid Equivalence Class partition: 100 to 999 inclusive. Non-valid Equivalence Class partitions: less than 100, more than 999, decimal numbers and alphabets/non-numeric characters.

In equivalence-partitioning technique we need to test only one condition from each partition. This is because we are assuming that all the conditions in one partition will be treated in the same way by the software. If one condition in a partition works, we assume all of the conditions in that partition will work, and so there is little point in testing any of these others. Similarly, if one of the conditions in a partition does not work, then we assume that none of the conditions in that partition will work so again there is little point in testing any more in that partition.