3 Cesare Pautasso 2005 JOpera: an Agile Environment for Web Service Composition with Visual Unit Testing and Refactoring Proc. of the 2005 IEEE Symposium on Visual Languages and Human Centric Computing (VL/HCC'05) Dallas, TX September 2005 Agile methodologies employ light-weight development practices emphasizing a test-driven approach to the development of software systems. Modern agile development environments support this approach by providing tools that automate most of the work required to effectively deal with change, including unit testing and different forms of refactoring. In this paper we discuss how to apply such techniques within the JOpera Visual Composition Language. More precisely, we show how we used the visual language to implement a regression testing framework for compositions written in the language itself, and how we introduced support in the visual environment for refactorings such as renaming, synchronization of service interface changes, and extraction/inlining across different levels of nesting. This is done in the context of the Web service composition tools provided with the JOpera for Eclipse research platform.