DB Connection test for php

db_connect_test.php

<?php
$active_group = 'default';
$query_builder = TRUE;

$db['default'] = array(
    'dsn'          => '',
    'hostname'     => '127.0.0.1', // better than localhost if mysqli.default_socket points to a unknown path
    'username'     => 'db_user', // As of MySQL v5.7, you can't use 'root' without sudo - you must use a different username and password - https://askubuntu.com/questions/763336/cannot-enter-phpmyadmin-as-root-mysql-5-7
    'password'     => 'password',
    'database'     => 'dbname',
    'dbdriver'     => 'mysqli',
    'dbprefix'     => '',
    'pconnect'     => FALSE,
    'db_debug'     => TRUE,
    'cache_on'     => FALSE,
    'cachedir'     => '',
    'char_set'     => 'utf8',
    'dbcollat'     => 'utf8_general_ci',
    'swap_pre'     => '',
    'encrypt'      => FALSE,
    'compress'     => FALSE,
    'stricton'     => FALSE,
    'failover'     => array(),
    'save_queries' => TRUE
);

/* Connection test: */

echo '<pre>';
print_r($db['default']);
echo '</pre>';

echo 'Connecting to database: ' .$db['default']['database'];

$mysqli_connection = new MySQLi($db['default']['hostname'],
                                $db['default']['username'],
                                $db['default']['password'],
                                $db['default']['database']);

if ($mysqli_connection->connect_error) {
   echo "Not connected, error: " . $mysqli_connection->connect_error;
}
else {
   echo "Connected.";
}
die( 'file: ' .__FILE__ . ' Line: ' .__LINE__);