添加操作无响应

I am trying to build a simple wordpress plugin and I encountered an issue with add_action function.

In my main php, I did

function menu_register(){
         .
         .
         .
    add_submenu_page( self::$menu_slug, self::$test_gp_title, self::$test_gp_page_title,  self::$capabilities, self::$test_gp_slug, array(__CLASS__, "menu_gp_db"));
}

and

    function menu_gp_db(){
        include_once(plugin_dir_path( __FILE__ )."ui/drag_and_drop.php");   
    }

In my drag_and_drop.php, I realized add_action functions do not work at all.

echo "TEST";
class myTest { 
    function __construct() {
        echo "what is going on?";
    }
}

function tree_survey_init2(){
    global $myTest;
    $myTest = new myTest(); 
}   
function myTest(){
  echo "ABC";
}

add_action("init","tree_survey_init2");
add_action("myTest","myTest");
echo "END";

The result is

TEST

END

Can I get some advice?

You are trying to add the class, functions and hooks inside add_sumenu_page callback function:

function menu_gp_db(){
    echo "TEST";
        class myTest { /**/ }
        function tree_survey_init2(){ /**/ }   
        function myTest(){ /**/ }
        add_action("init","tree_survey_init2");
        add_action("myTest","myTest");
    echo "END";
}

When it should be only:

function menu_gp_db(){
    echo "TEST";
    echo "END";
}

I think you can merge the rest of code back inside main.php.