Type Profiling to the Rescue: Test Amplification in Python and Smalltalk

Abstract

Software test amplification is the act of strength-ening manually written test-cases to exercise the boundary conditions of the system under test. It has been demonstrated by the research community to work for the programming language Java, relying on the static type system to safely transform the code under test. In dynamically typed languages, such type decla-rations are not available, and as a consequence test amplification has yet to find its way to programming languages like Smalltalk, Python, Ruby and Javascript. The AnSyMo research group has created two proof of concept tools for languages without a static type system: AmPyfier (for Python) and Small-Amp (for Pharo-Smalltalk). In this tool demonstration paper we explain how we relied on profiling libraries present in the respective eco-systems to infer the necessary type information for enabling full-blown test amplification.