wait statement must contain condition clause with UNTIL keyword

问题

The following VHDL is to be used to test bench. I keep getting an error on the first wait statement during analysis : "wait statement must contain condition clause with UNTIL keyword" I have several working test benches written this way. I can't seem to find what the error might be.

`library IEEE;
USE IEEE.std_logic_1164.all;
entity case_ex_TB is end;
architecture simple_test of case_ex_TB is
--- DUT Component Declaration ---
component case_ex
    port(
    clk, rstN: IN std_logic;
    color: OUT std_logic_vector(2 downto 0));
end component;
--- Signals Declaration ---
signal rst, clock: std_logic:='0';
signal color: std_logic_vector(2 downto 0);

begin
DUT: case_ex  --- DUT instantiation ---
port map (clk => clock,
         rstN => rst,
         color => color);
--- Signal's Waves Creation ---
rst <= '1','0' after 50 ns, '1' after 2 us;
clock_crtate: process
begin
    while rst = '0' loop
        clock <= '1','0' after 50 ns;
        wait for 100 ns;
    end loop;
        clock <= '1';
        wait;
end process;
end simple_test;`

回答1:

You get this error because you have set your testbench as the top-level entity in Quartus-II. The top-level entity must remain the component case_ex, and this component must contain synthesizable code.

To simulate your testbench, you must configure a testbench. Just klick on the plus-sign before "RTL Simulation" and then "Edit Settings". (Names may differ with Quartus version).

来源：https://stackoverflow.com/questions/33782358/wait-statement-must-contain-condition-clause-with-until-keyword