Detecting behavioural changes when refactoring a web-based legacy system

Sammanfattning: Legacy code suffers from poor readability and testability. This together with ever changing business requirements leads management and development teams to prioritize quick fixes over risky restructuring of working code. It is clear that the technical debt accumulated through inadequate maintenance will create a sinking ship. The dilemma of having to change code to increase test coverage, to guard against the introduction of bugs withstands. Characterization testing is a form of automated testing where the goal is to detect behaviour changes rather than to ensure program correctness. This master thesis aims to develop a tool which allows for characterization testing without first changing the code under test. Using only URL's to create test cases for the web application and ensuring that the server response is the same before and after a refactorization.