What is an equivalence partition? Give an example.

What is an equivalence partition? Give an example.
Answer: Equivalence partitioning is an effective approach to testing because it helps account for errors that programmers often make when processing inputs at the edges of partitions. You can also use testing guidelines to help choose test cases. Guidelines encapsulate knowledge of what kinds of test cases are effective for discovering errors. For example, when you are testing programs with sequences, arrays, or lists, guidelines that could help reveal defects include:

1. Test software with sequences that have only a single value. Programmers naturally think of sequences as made up of several values and sometimes they embed this assumption in their programs. Consequently, if presented with a single value sequence, a program may not work properly.

2. Use different sequences of different sizes in different tests. This decreases the chances that a program with defects will accidentally produce a correct output because of some accidental characteristics of the input.

3. Derive tests so that the first, middle, and last elements of the sequence are accessed. This approach reveals problems at partition boundaries.