StateSpecs (package separated from Mocketry) implements it. And such "should" syntax extendable by pragmas. Your example looks like:
[exp] should raise: Error
It is implemented with main spec class RaisingExceptionSpec
RaisingExceptionSpec >>basicMatches: aBlockContext
��� [aBlockContext value.
�� ^false] on: requiredException
��� ��� ��� do:
��� ��� ��� ��� [:ex |
��� ��� ��� ��� ex class = SpecFailed ifTrue: [ex outer].
��� ��� ��� ��� ^true]
And single method in special DSL class:
Raise>>exception: aClass
��� <syntax: #(raise:)>
��� ^RaisingExceptionSpec requiredException: aClass