Concolic Testing for Functional Languages

Concolic testing is a software testing technique combining concrete execution of a program (given specific input, along specific paths) with symbolic execution (generating new test inputs that give better path coverage than random test case generation). Concolic testing has so far been applied, mainly at the level of bytecode or assembly code, to programs written in imperative languages that manipulate primitive data types such as integers and arrays. In this paper, we demonstrate its application to a functional programming language core, a subset of the core language of Erlang, that supports pattern matching, structured recursive data types such as lists, recursion and higher-order functions. Moreover, we present CutEr, a tool implementing this testing technique. We describe CutEr's architecture, the challenges that need to be addressed by such a tool, its current limitations, and report some experiences from its use.