MT - 62 - Orthogonal Array(OATS) !

Before discussing about orthogonal array let me take an example of a real time testing scenario. Suppose there is a requirement of testing where we need to test 3 parameters with 3 different values in a system. So here to do exhaustive testing and see the response of every possible input we need to have 27 test data sets.

So here comes the concept of Orthogonal arrays.This technique is used when we have to test with huge number data having many permutations and combinations.This technique maximizes the coverage with lesser number of test cases. I'd say this technique guarantees 100% coverage with comparatively lesser no of cases.
Now we map each values with the parameters. To do the mapping we need to identify all the parameters(also called as factors and values. Then make a table with all the possible combinations saying that each row is unique So here we can see that all the permutations and combinations are possible in 9 cases only. We can write our test sets based on the parameters and values.

Orthogonal Array based on parameter and value

Test data sets ↓	Parameter 1	Parameter 2	Parameter 3
1	Value 1	Value 1	Value 3
2	Value 1	Value 2	Value 2
3	Value 1	Value 3	Value 1
4	Value 2	Value 1	Value 2
5	Value 2	Value 2	Value 1
6	Value 2	Value 3	Value 3
7	Value 3	Value 1	Value 1
8	Value 3	Value 2	Value 3
9	Value 3	Value 3	Value 2

Now once the array is created and we do testing there is a possibility of defects. There may be a single mode or multimode faults which we need to confirm seeing the parameters and values. Let's see it one by one :

Single Mode Faults - Single mode faults occur only due to one parameter. For example, in above Orthogonal array if test cases 7, 8 and 9 show error, we can expect that value 3 of parameter 1 is causing the error. Likewise we can detect as well as isolate the error.

Double Mode Fault - Double mode fault is caused by the two specific parameters values interacting together. Such an interaction is a harmful interaction between interacting parameters.

Multimode Faults - If more than two interacting components produce the consistent erroneous output, then it is a multimode fault. Orthogonal array detects the multimode faults.


Some important points :
- Creates an efficient and concise test set with many fewer test cases than testing all combinations
of all variables.

- This technique exercises some of the complex combinations of all the variables.

- It is simpler to generate and less error prone than test sets created by hand.
- This is a type of black box testing techniques.
-Orthogonal arrays can be applied in user interface testing, system testing, regression testing, configuration testing and performance testing
-OAT, is a systematic and statistical approach to pairwise interactions.
- Test cycle time is reduced