Unit testing for a PHP file

I need to create a test file for this code which I am going to upload.

// Create connection

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {

    die("Connection failed: " . $conn->connect_error);
} else {

    //echo "<Strong>Connection Successful</Strong>", "<br>" ;
}
?>

Could you please help me create a testing file for this php code?