获得类别的custompost

I have issue with getting all posts with a category("case"), if I remove the 'cat' => $cat_id line i get all posts in posttype "Feed"

How do I get out only posts with category 'case'?

$cat_id = get_cat_ID('case');
var_dump($cat_id); //responce is 40
$args = array(
    'post_type' => 'Feed',
    'posts_per_page' => -1,
    'cat' => $cat_id, 
  );

while ( $loop->have_posts() ) : $loop->the_post();
    var_dump($loop);
endwhile;
wp_reset_query();

            <ul>
            <?php
                global $post;
                $args = array( 'category' => 'your category name id''offset'=> 1, );
                $myposts = get_posts( $args );
                foreach( $myposts as $post ) :  setup_postdata($post); ?>
                    <li class="testimonial"><?php the_content(); ?></li><br/>
                <?php endforeach; ?>
            </ul>
        <?php } ?>

for more information check https://codex.wordpress.org/Template_Tags/get_posts

Please try this code : change your category id or post id

<?php if (is_category('3') ) { ?>
 <?php query_posts('p=17'); ?>
 <?php while (have_posts()) : the_post(); ?>
   <h4><?php the_title(); ?></h4>
   <?php the_content(); ?>
 <?php endwhile;
} elseif (is_category('13') ) { ?>
 <?php query_posts('p=11'); ?>
 <?php while (have_posts()) : the_post(); ?>
   <h4><?php the_title(); ?></h4>
   <?php the_content(); ?>
 <?php endwhile;
} else { ?>
 //whatever goes in here
<?php } ?>