Find entries w/ category relation in Matrix block (Craft CMS)

gistfile1.twig

{# Fetch the category "myCategory" (and any child categories as well) #}
{% set categories = craft.categories.slug( 'myCategory' ) %}

{# Search for entries in section "test", that has the category "myCategory" (or any of its child categories) selected in the field "category" of the Matrix block "testMatrix" #}
{% set entries = craft.entries.section( 'test' ).relatedTo({
	targetElement: categories,
	field: 'testMatrix.category'
}) %}

{# Output the entries #}
{% for entry in entries %}
	{{ entry.title }}<br/>
{% endfor %}

{# Output the categories we filtered against, too #}
{% for category in categories %}
	{{ category.title }}
{% endfor %}

This works perfectly !!! Thank you so much!