Loop Testing

Loops are the basis of most algorithms implemented using software.Loop testing is a white box testing approach that concentrates on the validity of loop constructs.Four loops 
can be defined: simple loops, concatenate loops, nested loops, and unstructured loops.

1.Simple loops: The follow group of tests should be used on simple loops, where n is the maximum number of allowable passes through the loop: 

� Skip the loop entirely.

� Only one pass through the loop.

� Two passes through the loop.
� M passes through the loop where m<n.
� n-1, n, n+1 passes through the loop.


2.Nested loop: For the nested loop the number of possible tests increases as the level of nesting grows. This would result in an impractical number of tests. An approach that 
will help to limit the number of tests:

� Start at the innermost loop. Set all other loops 
to minimum values.
� Conduct simple loop tests for the innermost loop 
while holding the outer loop at their minimum iteration 
parameter value. 
� Work outward, performing tests for the next loop, 
but keeping all other outer loops at minimum values and 
other nested loops to typical values.
� Continue until all loops have been tested.


3.Concatenated loops: Concatenated loops can be tested using the techniques outlined for simple loops, if each of the loops is independent of the other. When the loops are not independent the approach applied to nested loops is recommended.

4.Unstructured loops: This class of loop should be 
redesigned to reflect the use of the structured programming 
constructs.