Smother: an MC/DC analysis tool for Erlang

This paper discusses an MC/DC analysis tool built for the Erlang programming language. Code coverage metrics are one way to measure the adequacy of a test suite, however, despite widespread industrial use in business-critical software, the only coverage metric readily available for Erlang is statement coverage, provided by the Cover tool that is distributed by the OTP standard libraries. An alternative to statement cover is Multiple Condition/Decision Coverage (MC/DC) -- one of the most extensive coverage metrics, which is mandated by many software safety standards. Here we describe the application of MC/DC analysis to Erlang programs, and include an extension to traditional MC/DC analysis that applies the underlying philosophy to the pattern matching decision structures of functional languages. We have implemented the approach in the Smother tool that we also describe here as well as its use by our industrial project partners.