WP Shortcode with multi properties

plugin.php

function my_testimonial_accordion($atts){
ob_start();
$newcat = shortcode_atts(array(
  'testcat' => '',
), $atts );

if ( $newcat['testcat'] ) {
  // Parse type into an array. Whitespace will be stripped.
  $newcat['testcat'] = array_map( 'trim', str_getcsv( $newcat['testcat'], ',' ) );
}
$output = $newcat['testcat'];

$testargs = array(
 'post_type' => 'testimonial', // Change CPT
 'posts_per_page' => -1,
 'tax_query' => array(
	array(
	'taxonomy' => 'type', // Change to custom tax
	'field' => 'slug',  
	'terms' => $output,
  ),
 ),
);
$testloop = new WP_Query( $testargs ); 
?>
<div class="grid">
	<?php if ( $testloop->have_posts() ) :
		while ( $testloop->have_posts() ) : $testloop->the_post(); ?>
			<div class="testimonial-tiles" style="width:100%;text-align:left;">
				<h5><?php the_title(); ?></h5>
				<p><?php the_content(); ?></p>
			</div>
		<?php
		endwhile;
	endif; ?>
</div>
<?php
wp_reset_postdata();
return ob_get_clean();
}
add_shortcode('my_testimonial','my_testimonial_accordion');