Visual Assurance in Refactoring Through Trace Equivalence of Control Flow Graphs

Refactoring large legacy codebases, even with industrial-strength tools, often leads to trust concerns with code owners, in particular when the codebase underwent significant changes. To provide more assurance to code owners, we integrate visual analytics into the refactoring process. This method involves transforming code into control flow graphs before and after refactoring, followed by trace equivalence analysis on these graphs. An innovative visualisation tool provides not only a comprehensive overview of the refactorings' impact across all files, but also offers detailed insights into the trace equivalence at individual file level. By presenting clear visual evidence of code equivalence before and after refactoring, our visualisation narrows the trust gap, offering refactoring experts and code owners a transparent and understandable view of the changes. We apply this visualisation on an industrial use case and discuss its effectiveness with refactoring experts.