Reducing Technical Debt Density: Refactoring vs. Writing Clean New Code

Technical Debt (TD) is a powerful metaphor that represents shortcuts taken in a software development project, usually to meet business goals such as limited time or budget. TD concerns mostly invisible parts of the system (i.e. no visible features or defects) and has a detrimental effect on the maintainability and evolvability of software. TD manifests in both design and implementation constructs such as sub-optimal design decisions, design and code smells, use of impertinent technologies, lack of documentation etc.Technical Debt cannot realistically be eliminated but it does need to be proactively managed in order to be kept at a sustainable level. Managing Technical Debt is comprised of a number of activities. In this thesis, we focus on two of these activities, which are reported in the literature as the most important: repayment and prevention. As its name suggests, repayment refers to the remediation of TD by reworking the aforementioned design and implementation constructs; consider for example refactoring the source code, optimizing a design decision or documenting architecture knowledge that has remained tacit. Similarly, prevention of TD refers to ensuring the underlying issues will not occur in the first place; consider for example, checking for source code violations, supporting design decision making to avoid future maintenance overhead or simply allocating enough resources to follow the right approach instead of the "quick and dirty" one. In this thesis, we investigate to what extent repayment (through refactoring) and prevention (through writing clean new code) are effective in managing Technical Debt