Software testability is coming out to be most frequent talked about subject then the underrated and unpopular quality factor it used to be in past few years. The correct and timely assessment of testability can lead to improvisation of software testing process. Though many researchers and quality controllers have proved its importance, but still the research has not gained much momentum in emphasizing the need of making testability analysis necessary during all software development phases. In this paper we review and analyse the factors affecting testability estimation of object oriented software systems during design and analysis phase of development life cycle. These factors are then linked together in the form of new assessment model for object oriented software testability. The proposed model will be evaluated using analytical hierarchical process (AHP).