LIBRARY ieee;
USE ieee.std_logic_1164.ALL;

ENTITY pass_thru_tb IS
END pass_thru_tb;
 
ARCHITECTURE behavior OF pass_thru_tb IS 
 
    -- Component Declaration for the Unit Under Test (UUT)
 
    COMPONENT pass_thru
    PORT(
         button_north : IN  std_logic;
         button_south : IN  std_logic;
         button_west : IN  std_logic;
         button_east : IN  std_logic;
         switches : IN  std_logic_vector(3 downto 0);
         leds : OUT  std_logic_vector(7 downto 0)
        );
    END COMPONENT;

   --Inputs
   signal button_north : std_logic := '0';
   signal button_south : std_logic := '0';
   signal button_west : std_logic := '0';
   signal button_east : std_logic := '0';
   signal switches : std_logic_vector(3 downto 0) := (others => '0');

 	--Outputs
   signal leds : std_logic_vector(7 downto 0);
	
	--Clock
	signal clock : std_logic := '0';
   constant clock_period : time := 20 ns;
 
BEGIN
 
	-- Instantiate the Unit Under Test (UUT)
   uut: pass_thru PORT MAP (
          button_north => button_north,
          button_south => button_south,
          button_west => button_west,
          button_east => button_east,
          switches => switches,
          leds => leds
        );

   -- Clock process definitions
   clock_process :process
   begin
		clock <= '0';
		wait for clock_period/2;
		clock <= '1';
		wait for clock_period/2;
   end process;

   -- Stimulus process
   stim_proc: process
   begin		
      -- hold reset state for 10 ns.
		button_north <= '0';
		button_south <= '0';
		button_west <= '0';
		button_east <= '0';
		switches <= X"0";
      wait for 10 ns;
      wait for clock_period;

      -- insert stimulus here 
 		--Error Check OFF
		button_north <= '0';
		button_south <= '0';
		button_west <= '0';
		button_east <= '0';
		switches <= X"0";
		wait for clock_period;
		Assert ( leds = X"00" )
			Report "Error : leds = x00"
			Severity ERROR;

 		--Error Check ON
		button_north <= '1';
		button_south <= '1';
		button_west <= '1';
		button_east <= '1';
		switches <= X"F";
		wait for clock_period;
		Assert ( leds = X"FF" )
			Report "Error : leds = xFF"
			Severity ERROR;		
			
      wait;
   end process;

END;