oh!!!! Kewl the topic now entered into Debugging!!!! :-)

After the initial testing is complete, mutation testing is 
taken up. The idea behind mutation testing is to make a few 
arbitrary small changes to a program at a time, each
time the program is changed it is called a mutated program; 
the change is called a mutant.

A mutated program tested against the full test suite of the 
program. If there at least one test case in the test suite 
for which a mutant gives an incorrect result, then the 
mutant is said to be dead. 

If a mutant remains alive even after all test cases have 
been exhausted, the test suite is enhanced to kill the 
mutant.

The process of generation and killing of mutants can be 
automated by predefining a set of primitive changes that 
can be applied to the program.

The primitive changes can be:
? Altering an arithmetic operator,
? Changing the value of a constant,
? Changing a data type, etc.

A major disadvantage of mutation testing:
? computationally very expensive,
? A large number of possible mutants can be generated.

Valid?????? :-)