Test-Driven Re-Engineering and Regression Verification

Lecture 31 of SE602 Software Re-Engineering advances testing methodologies into Test-Driven Re-Engineering (TDRE). Under TDRE, every planned refactoring or modularization step is preceded by the creation of targeted unit, integration, or contract tests that formalize the desired subsystem boundary. The lecture examines continuous integration (CI) pipelines that automatically execute regression suites upon every refactoring commit, preventing defect leakage into production branches. Students explore mutation testing to evaluate test suite quality, intentionally injecting faults into source code to ensure tests detect anomalies. The lesson concludes with formal behavioral preservation proofs, demonstrating how combining characterization safety nets with automated regression suites enables software engineers to refactor legacy systems with absolute confidence. The lesson explores cognitive program comprehension models, top-down hypothesis validation, and mental mappings of complex legacy architectures. Practical code illustrations demonstrate safe code transformations, automated refactoring preconditions, and behavioral equivalence preservation. Scholars analyze Chidamber-Kemerer object-oriented metrics including WMC, CBO, and RFC to quantify the architectural impact of refactoring. Cloud migration pathways including rehosting, replatforming, and cloud-native refactoring are examined as extensions of legacy modernization. The relationship between technical debt accumulation, architectural degradation, and long-term enterprise software viability is reinforced. In this lecture, students examine formal methodologies, structural transformations, and analytical metrics of software re-engineering systems. Through detailed theoretical breakdowns, the lesson explores software evolution dynamics, legacy system preservation, and maintainability enhancement. Special emphasis is placed on reverse engineering workflows, abstract syntax tree construction, and program dependency representations. Mastering these foundational software re-engineering paradigms empowers software engineers to systematically revitalize enterprise legacy platforms. Analytical exercises and architectural traces help students prepare thoroughly for Virtual University midterm and final term examinations. The curriculum systematically aligns theoretical software evolution principles with practical source code modernization across industrial codebases. Reviewing the accompanying lecture handouts and metric tables reinforces understanding of coupling, cohesion, and architectural decay. Consistent evaluation of control flow graphs, call graph hierarchies, and database schemas ensures robust preparation for academic assessments. Students investigate the trade-offs between system replacement, wrapping legacy components, and iterative code refactoring transformations.