Add an interface for the Channel Aggregate so we can test it easier.

app/src/Domain/Aggregate/ChannelAggregate.php

@@ -5,7 +5,7 @@ namespace Slovocast\Domain\Aggregate;
 use Slovocast\Domain\Entity\Episode;
 use Slovocast\Domain\Entity\Channel;
 
-class ChannelAggregate 
+class ChannelAggregate implements ChannelAggregateInterface
 {
     /**
      * @param Channel $channel

app/src/Domain/Aggregate/ChannelAggregateInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Slovocast\Domain\Aggregate;
+
+use Slovocast\Domain\Entity\Channel;
+use Slovocast\Domain\Entity\Episode;
+
+interface ChannelAggregateInterface
+{
+    public function getChannel(): Channel;
+
+    /**
+     * @return array<Episode>
+     */
+    public function getEpisodes(): array;
+    public function hasEpisodes(): bool;
+    public function addEpisode(Episode $episode): void;
+
+    /**
+     * @param array<Episode> $episodes
+     * @return void;
+     */
+    public function setEpisodes(array $episodes): void;
+
+}