Add heic encoder test

tests/Drivers/Imagick/Encoders/HeicEncoderTest.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Drivers\Imagick\Encoders;
+
+use Imagick;
+use ImagickPixel;
+use Intervention\Image\Drivers\Imagick\Core;
+use Intervention\Image\Drivers\Imagick\Driver;
+use Intervention\Image\Encoders\HeicEncoder;
+use Intervention\Image\Image;
+use Intervention\Image\Tests\TestCase;
+use Intervention\Image\Tests\Traits\CanCreateImagickTestImage;
+
+/**
+ * @requires extension imagick
+ */
+final class HeicEncoderTest extends TestCase
+{
+    use CanCreateImagickTestImage;
+
+    protected function getTestImage(): Image
+    {
+        $imagick = new Imagick();
+        $imagick->newImage(3, 2, new ImagickPixel('red'), 'jpg');
+
+        return new Image(
+            new Driver(),
+            new Core($imagick)
+        );
+    }
+
+    public function testEncode(): void
+    {
+        $image = $this->getTestImage();
+        $encoder = new HeicEncoder(75);
+        $result = $encoder->encode($image);
+        $this->assertMediaType('image/heic', (string) $result);
+    }
+}