pattern name for override view templates Twig template - views-view-unformatted.html.twig contains :

#}
{% if title %}
&lt;h3&gt;{{ title }}&lt;/h3&gt;
{% endif %}
{% for row in rows %}
{%
set row_classes = [
default_row_class ? 'views-row',
]
%}
&lt;div{{ row.attributes.addClass(row_classes) }}&gt;
{{ row.content }}
&lt;/div&gt;
{% endfor %}


I want to insert a &lt;hr&gt; tag after each &lt;/div&gt;:

&lt;div{{ row.attributes.addClass(row_classes) }}&gt;
{{ row.content }}
&lt;/div&gt;
&lt;hr&gt;
{% endfor %}


It works, but for all and every {{ row.content }}. I want to do it only for certain views-blocks. Twig debugging offers me to theme a whole block (for example: block--views-block--news-left-block-1.html.twig) and I need something like views-view-unformatted--news-left-block-1.html.twig or some other way to insert the tag.

what is the correct filename to override view template?

Thank you.
Just use  views-view-unformatted--(your view block name).html.twig.
Eg. If your view name is Slideshow, use views-view-unformatted--slideshow.html.twig

This is a good reference point - http://redcrackle.com/blog/drupal-8/theme-views-templates