In reply to chr_sue:
1 @ (posedge vif.clk); 2 vif.int_a = seq.int_a; 3 vif.int_b = seq.int_b; 4 seq.outp = seq.int_a + seq.int_b;
why are you using line-4 hear, Tb only for stimulus generation purpose, why you using design in TB.