To query for multiple post types you would add an array() of post types instead of just querying for one.
$args = array(
'post_type' => array( 'testimonial', 'post' ),
'posts_per_page' => 1,
$query = new WP_Query( $args );
If you like this question & answer and want to contribute, then write your question & answer and email to freewebmentor[@]gmail.com. Your question and answer will appear on FreeWebMentor.com and help other developers.