module test();

wire signed [7:0] value1;
wire        [7:0] value2;

assign value1[3:0] = 4'd2;

assign value2 = abs(value1);

initial begin
  #2 $display("%b %b", value1, value2);
  if (value2 === 8'bx)
    $display("PASSED");
  else
    $display("FAILED");
end

endmodule