I am working on synthesizing generated ATPG test vectors and Implement them on an FPGA , however there'S plenty of DON'T CARE Values 'X', in the stimuli and response vectors, I am not sure how the synthesizer will treat the 'X' values, which will make test vectors comparison to fail, is there  a technique on how to implement test vectors with plenty of 'X' values ? 
I am coding in Verilog, my vector length is around 1911 bit with more than 200 vectors to be tested

Thanks