  Unit testing frameworks are nowadays considered a best practice, included in
almost all modern software development processes, to achieve rapid development
of correct specifications. Knowledge representation and reasoning paradigms
such as Answer Set Programming (ASP), that have been used in industry-level
applications, are not an exception. Indeed, the first unit testing
specification language for ASP was proposed in 2011 as a feature of the ASPIDE
development environment. Later, a more portable unit testing language was
included in the LANA annotation language. In this paper we revisit both
languages and tools for unit testing in ASP. We propose a new unit test
specification language that allows one to inline tests within ASP programs, and
we identify the computational complexity of the tasks associated with checking
the various program-correctness assertions. Test-case specifications are
transparent to the traditional evaluation, but can be interpreted by a specific
testing tool. Thus, we present a novel environment supporting test driven
development of ASP programs.
