wordpress: login to a user "avni_temp_user" and then log out

<?php
function temp_user_login(){
  $user_id = username_exists( 'avni_temp_user' );
  if( !$user_id and email_exists( 'avni_temp_user@gmail.com' ) == false ) {
    // Create a new user
    $random_password = wp_generate_password( $length=12, $include_standard_special_chars=false );
    $user_id = wp_create_user( 'avni_temp_user', $random_password, 'avni_temp_user@gmail.com' );
  } else {
    // Get user data
    $user = get_user_by( 'id', $user_id );
  }
  // Login
  wp_set_current_user( $user_id, $user_login );
  wp_set_auth_cookie( $user_id );
  do_action( 'wp_login', $user_login );
  wp_logout();
}