two_hot.sv

// Randmly generate Two-hot (Having 2 one) variable having length of 5 bit
class rand_twohot #(int unsigned L = 5);
  rand int unsigned a;
  rand int unsigned b;
  logic [L-1:0] two_hot;

  constraint cn_1 {
    a != b;
    a >= 0; a < L;
    b >= 0; b < L;
  }
  
  function void post_randomize();
    two_hot = (1 << a) | (1 << b);
  endfunction
endclass

module top();
  rand_twohot TH;
  initial begin
    repeat (5) begin
      TH = new();
      if (TH.randomize()) begin
        $display ("Th.a=%0d, TH.b=%0d, TH.two_hot=%b", TH.a, TH.b, TH.two_hot);
      end
      else begin
        $error ("Randomization failed");
      end
    end
  end
endmodule

//Output:
// Th.a=3, TH.b=4, TH.two_hot=11000
// Th.a=1, TH.b=4, TH.two_hot=10010
// Th.a=3, TH.b=1, TH.two_hot=01010
// Th.a=2, TH.b=1, TH.two_hot=00110
// Th.a=3, TH.b=4, TH.two_hot=11000