Quality assurance is one of the important non-functional software requirements which many software products fail to satisfy. Current software market is driven mostly by urgency and competition. This poses a erious problem to software quality assurance, customer satisfaction and reliability of the software products. One of the methods to ensure software quality is a metrics-based approach. Software metrics have been used to quantitatively evaluate software products. Software metrics proposed and used for procedural paradigm have been found inadequate for object-oriented software products, mainly because of the distinguishing features of the object-oriented paradigm such as inheritance and polymorphism. In this thesis, we propose a new set of metrics for object-oriented software; this set is targeted towards evaluating the efforts required for testing object-oriented programs. The new metrics have been analytically evaluated using widely known properties for software metrics. They have also been critically compared with other metrics published in the literature. Experimental evaluation of these metrics have also been presented in the thesis.