  We provide a general formulation for the code-based test compression problem
with fixed-length input blocks and propose a solution approach based on
Evolutionary Algorithms. In contrast to existing code-based methods, we allow
unspecified values in matching vectors, which allows encoding of arbitrary test
sets using a relatively small number of code-words. Experimental results for
both stuck-at and path delay fault test sets for ISCAS circuits demonstrate an
improvement compared to existing techniques.
