ImageMagick PNG encoder test

tests/Drivers/Imagick/Encoders/PngEncoderTest.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Drivers\Imagick\Encoders;
+
+use Imagick;
+use ImagickPixel;
+use Intervention\Image\Collection;
+use Intervention\Image\Drivers\Imagick\Encoders\PngEncoder;
+use Intervention\Image\Drivers\Imagick\Frame;
+use Intervention\Image\Drivers\Imagick\Image;
+use Intervention\MimeSniffer\MimeSniffer;
+use Intervention\MimeSniffer\Types\ImagePng;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @requires extension imagick
+ */
+final class PngEncoderTest extends TestCase
+{
+    protected function getTestImage(): Image
+    {
+        $imagick = new Imagick();
+        $imagick->newImage(3, 2, new ImagickPixel('red'), 'jpg');
+        $frame = new Frame($imagick);
+
+        return new Image(new Collection([$frame]));
+    }
+
+    public function testEncode(): void
+    {
+        $image = $this->getTestImage();
+        $encoder = new PngEncoder(75);
+        $result = $encoder->encode($image);
+        $this->assertTrue(MimeSniffer::createFromString((string) $result)->matches(new ImagePng()));
+    }
+}