This dissertation investigates the factors that affect testability and testing cost of object- oriented software systems. Developing a software program which eases the testing process by increasing testability is crucial. Also, to assess whether or not the testing effort and cost consumed or planned is adequate or not is another critical matter this dissertation aims to answer by composing a new way to evaluate the links between software design parameters and testing effort via source-based metrics. An automated metric plug-in is used as the primary tool for obtaining the metric measurements. Our study is based on the investigation of many open-source projects written in Java to achieve our goals. By the help of the statistical evaluation of project data, we both propose a new model to assess testing effort and testability, and find significant relations and associations between software design and testing effort and testability of object-oriented software systems via source-based metrics.

Context: Software testability, which is the degree to which a software artifact facilitates process of testing, is not only the indication of the test process effectiveness but also gives the new perspective on code development. Since more than fifty percent of total software development costs is related to testing process activities, Software testability has always been the improving area in software domain so that we can make the software development process effective with respect to test cases writing and fault detection process. Objectives: The research though this thesis will have the objective of proposing a conceptual framework considering the testability issues for the simpler test suite generation and facilitating the concerned persons with better effectiveness of testing. We investigate the testability factors and testability metrics basically with the help of the systematic literature review and the proposed framework’s feasibility is evaluated with case study. Methods: Initially, we conduct the literature review to get broad knowledge on this domain as well for the key documents. Then study starts with the systematic literature review process guided by the review protocol to collect the testability factors and measurements. The framework is validated with the case study. The research documents are included from highly trusted e-database including Compendex, Inspec, IEEE Xplore, ACM Digital Library, Springer Link and Scopus. Altogether 36 primary documents are included for the study and results are extracted. Results: From the results of systematic literature review, Software testability factors and associated measurements are found and the construction of framework for simple test generation as guidelines evaluate with case study. To make the test suite generation simpler, we propped a framework based on the FTA concepts and breakdown of high level testability factors to its simpler form of measureable level. Conclusions: Numbers of different software testability factors are presented in different researches in different perspectives. We collect important testability factors and associated measurement methods and we concluded the effect of testability in simpler test suite generation with the help of framework evaluated by case study.