  In this paper we investigate fair computations in the pi-calculus. Following
Costa and Stirling's approach for CCS-like languages, we consider a method to
label process actions in order to filter out unfair computations. We contrast
the existing fair-testing notion with those that naturally arise by imposing
weak and strong fairness. This comparison provides insight about the
expressiveness of the various `fair' testing semantics and about their
discriminating power.
