Custom post Title

Hi, I have a testimonial design and want to link strong testimonials to this. What is the post type you use for the array as when I use ‘testimonials’ or ‘testimonial’ it returns no posts. Here is my array.

<?php
$testimonial_args = array(
‘post_type’ => ‘testimonials’,
‘posts_per_page’ => 50
);
$testimonial_query = new WP_Query( $testimonial_args );
?>

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