Impact of Refactoring on Code Quality Improvement in Software Maintenance

Quality software are robust, reliable and easy to maintain, and therefore reduces the cost of software maintenance. But as software systems undergo modifications, improvements and enhancements to cope with evolving requirements, quality of software can be decreased. Refactoring is one of the methods which have been applied to improve software quality. Supporters claim that it helps increasing the quality of the code, making it easier to understand, modify and maintain. However, there is only limited empirical evidence of such assumption. Therefore it is sometimes difficult to judge whether the refactoring in question should be applied or not without knowing the effect accurately. The purpose of this study is to validate/invalidate the claims that refactoring improves software quality. Experimental research approach is used to achieve the main objectives of this study which is to quantitatively measure the impact of refactoring on code quality improvement in software maintenance. Ten refactoring techniques were evaluated through the experiment in order to access Resource Utilization, Changeability and Analysability which are ISO sub Quality factors. The result for analysability shows a slight advantage for refactoring, but the assumption of increased analysability does not answered from the analysability test. Concerning changeability, both the result and hypothesis test shows disadvantage for refactored code. The analysis of resource utilization also provides hints on disadvantages of the refactoring technique like increase resource consumption in terms of obtained disk space by source files.