Drupal 8 - Twig template won't get variables values - twig

Question

I'm trying to make a twig template to get a variable from a custom block, when I do a {{ dumb() }} it shows me the variables and their values but when I call for the variable it won't show it, even when i call the variable with dumb {{ dumb(title) }} it tells me is NULL. Could anyone help me understand what is the mistake?
Block: onyx_experiencia.php
/**
* Provides a 'Test' Block.
*
* #Block(
* id = "onyx_experiencia",
* admin_label = #Translation("Servicios OnyxGroup"),
* category = #Translation("Servicios OnyxGroup"),
* )
*/
class onyx_experiencia extends BlockBase implements BlockPluginInterface {
/**
* {#inheritdoc}
*/
public function build() {
$title = 'TestTitle34';
$desc = 'Test text 24';
$test_array = array(
'#title' => $title,
'#description' => $desc
);
return $test_array;
}
block.module: onyx_experiencia.module
<?php
/**
* Implements hook_theme().
*/
function onyx_experiencia_theme($existing, $type, $theme, $path) {
return array(
'block__serviciosonyxgroup' => array(
'template' => 'block--serviciosonyxgroup',
'render element' => 'elements',
'variables' => array(
'title' => 'TitleTest',
'description' => 'DescriptionTest'
),
),
);
}
Twig File: block--serviciosonyxgroup.html.twig
{#
/**
* #file
* Profile for onyx_experiencia block.
*/
#}
<h3>Featured Events</h3>
<p>Test: {{ title }} </p>
<p>Test: {{ description }} </p>
<ol>
{% for key, value in _context %}
<li>{{ key }}</li>
{% endfor %}
</ol>
{{ dump(content) }}
Result: This is the result i get
UPDATE Different way still not working

Answer 1

As seen on your screenshot:
The variables live in the variable content, not in _context
Your current template code assumes they in live _context though as they aren't prefixed with anything.
{{ title }} equals <?= isset($_context['title']) ? $_context['title'] : null; ?>
So u'd need to change the template to something like
<h3>Featured Events</h3>
<p>Test: {{ content['#title'] }} </p>
<p>Test: {{ content['#description'] }} </p>