PHPSpec implements a domain specific language (DSL) in PHP for specifying the behaviour of functional units such as methods and objects. The purpose of a DSL was to move away from the xUnit style declaration of tests towards a specification language centred on describing behaviour.
He illustrates with a bowling example - described with a sample class (with a itShouldScore0ForGutterGame test) and how to use it to fit his proposal:
My proposal therefore is to re-implement the current programming language DSL as a specification language - i.e. a new (extremely limited and narrow!) language capable of being parsed by PHPSpec into its PHP equivalent. [...] Using a specification DSL, we can simply ignore the existence of classes in PHP (well, the pretense is nice). Instead the DSL would incorporate a syntax for denoting shared behaviours.