Testability is an elusive idea, its precise estimation or assessment is a hard exercise. It is very tough to obtain an understandable view on all the probable factors that have positive impact on software testability. Researchers, practitioners and quality controllers have always argued that testability should be measured as a key attribute in order to promise the quality software. A faultless measure of software quality completely depends on testability measurement. The support provided by software testability is important throughout development life cycle and quality assurance.