diff --git a/.gitignore b/.gitignore
index 42359c5..768f5ae 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@
 /vendor/
 /.idea/
 /node_modules
+webroot/modified
diff --git a/composer.json b/composer.json
index 27e915c..5668234 100644
--- a/composer.json
+++ b/composer.json
@@ -39,6 +39,7 @@
 			"@phpstan",
 			"@psalm"
 		],
+		"test": "phpunit",
 		"stan-setup": "cp composer.json composer.backup && composer require --dev phpstan/phpstan:~1.9.0 psalm/phar:~5.4.0 && mv composer.backup composer.json",
 		"lowest-setup": "composer update --prefer-lowest --prefer-stable --prefer-dist --no-interaction && cp composer.json composer.backup && composer require --dev dereuromark/composer-prefer-lowest && mv composer.backup composer.json"
 	},
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..3ba0949
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,26 @@
+<?xml version="1.0"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="tests/bootstrap.php" colors="true" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+	<php>
+		<!-- E_ALL => 32767 -->
+		<!-- E_ALL & ~E_USER_DEPRECATED => 16383 -->
+		<ini name="error_reporting" value="16383"/>
+	</php>
+	<testsuites>
+		<testsuite name="assets">
+			<directory>tests/</directory>
+		</testsuite>
+	</testsuites>
+	<listeners>
+		<listener class="Cake\TestSuite\Fixture\FixtureInjector">
+			<arguments>
+				<object class="Cake\TestSuite\Fixture\FixtureManager"/>
+			</arguments>
+		</listener>
+	</listeners>
+	<!-- Prevent coverage reports from looking in tests, vendors, config folders -->
+	<coverage>
+		<include>
+			<directory suffix=".php">src/</directory>
+		</include>
+	</coverage>
+</phpunit>
diff --git a/src/Model/Entity/Asset.php b/src/Model/Entity/Asset.php
index 2d35c60..6f6517a 100644
--- a/src/Model/Entity/Asset.php
+++ b/src/Model/Entity/Asset.php
@@ -73,7 +73,15 @@ public function exists(): bool
      */
     protected function _getAbsolutePath(): string
     {
-        return ROOT . DS . $this->directory . DS . $this->filename;
+        $relativeOrAbsolute = DS . ltrim($this->directory . DS . $this->filename, DS);
+        if (is_readable($relativeOrAbsolute)) {
+            return $relativeOrAbsolute;
+        }
+        $path = ROOT . $relativeOrAbsolute;
+        if (is_readable($path)) {
+            return $path;
+        }
+        throw new \Exception('Could not find image file.');
     }
 
     /**
diff --git a/src/Utilities/ImageAsset.php b/src/Utilities/ImageAsset.php
index ed406aa..7865c25 100644
--- a/src/Utilities/ImageAsset.php
+++ b/src/Utilities/ImageAsset.php
@@ -3,7 +3,6 @@
 
 namespace Assets\Utilities;
 
-use App\View\AppView;
 use Assets\Error\FileNotFoundException;
 use Assets\Error\FilterNotFoundException;
 use Assets\Error\UnkownErrorException;
@@ -11,11 +10,14 @@
 use Cake\Core\Configure;
 use Cake\I18n\FrozenTime;
 use Cake\View\Helper\HtmlHelper;
+use Cake\View\View;
 use Intervention\Image\Image;
 use Intervention\Image\ImageManager;
+use InvalidArgumentException;
 use Nette\Utils\FileSystem;
 use Nette\Utils\Json;
 use Nette\Utils\Strings;
+use SplFileInfo;
 
 /**
  * To be called through Assets::getImage() with MimeType image/*
@@ -79,34 +81,38 @@ public function __construct(Asset $asset, int $quality = 90)
      * @param array $options - optional:
      * - title (string): for alt-parameter in html-output
      * - quality (int): for jpg compression
-     * @throws \Exception
+     * @throws \InvalidArgumentException when no file was found
      * @return \Assets\Utilities\ImageAsset
      */
     public static function createFromPath(string $path, array $options = [])
     {
-        $absolute_path = null;
-        $img_dir = WWW_ROOT . Configure::read('App.imageBaseUrl');
+        $absolute_path = false;
         if (file_exists($path)) {
             $absolute_path = $path;
-        } elseif (file_exists($img_dir . $path)) {
-            $absolute_path = $img_dir . $path;
+        } else {
+            $img_dir = WWW_ROOT . ltrim((string)Configure::read('App.imageBaseUrl'), DS);
+            if (file_exists($img_dir . $path)) {
+                $absolute_path = $img_dir . $path;
+            }
         }
 
-        if (!$absolute_path) {
-            throw new \Exception("Could not find image with path {$path}.");
+        if ($absolute_path === false || !is_readable($absolute_path)) {
+            throw new InvalidArgumentException("Could not find image with path {$path}.");
         }
 
-        $splFileInfo = new \SplFileInfo($absolute_path);
-
-        $asset = new Asset();
-        $asset->id = md5($path);
-        $asset->filename = $splFileInfo->getFilename();
-        $asset->directory = ltrim(str_replace(ROOT, '', $splFileInfo->getPath()), DS);
-        $asset->mimetype = mime_content_type($absolute_path) ?: 'unknown';
-        $asset->title = $options['title'] ?? null;
-        $asset->description = null;
-        $asset->modified = FrozenTime::createFromTimestamp($splFileInfo->getMTime());
-        $asset->created = $asset->modified;
+        $splFileInfo = new SplFileInfo($absolute_path);
+        $fileMTime = FrozenTime::createFromTimestamp($splFileInfo->getMTime());
+
+        $asset = new Asset([
+            'id' => md5($path),
+            'filename' => $splFileInfo->getFilename(),
+            'directory' => ltrim(str_replace(ROOT, '', $splFileInfo->getPath()), DS),
+            'mimetype' => mime_content_type($absolute_path) ?: 'unknown',
+            'title' => $options['title'] ?? null,
+            'description' => null,
+            'modified' => $fileMTime,
+            'created' => $fileMTime,
+        ]);
 
         $quality = $options['quality'] ?? 90;
 
@@ -251,7 +257,7 @@ public function getPath(): string
     public function getHTML(array $params = []): string
     {
         $path = $this->getPath();
-        $html = new HtmlHelper(new AppView());
+        $html = new HtmlHelper(new View());
 
         if (!$this->image) {
             $manager = $this->getImageManager();
@@ -313,7 +319,7 @@ private function getFilename(): string
      * @throws \Nette\Utils\JsonException
      * @throws \Assets\Error\FileNotFoundException
      */
-    private function getRelativePath(?\SplFileInfo $file = null): string
+    private function getRelativePath(?SplFileInfo $file = null): string
     {
         if ($file) {
             return $this->outputDirectory . $file->getFilename();
@@ -377,12 +383,12 @@ private function getAssetIdentifier(): string
      * @return \SplFileInfo|null
      * @throws \Nette\Utils\JsonException
      */
-    private function getFile(): ?\SplFileInfo
+    private function getFile(): ?SplFileInfo
     {
         $path = WWW_ROOT . ltrim($this->outputDirectory, DS) . $this->getFilename() . '.' . $this->format;
 
         if (file_exists($path)) {
-            return new \SplFileInfo($path);
+            return new SplFileInfo($path);
         }
 
         return null;
diff --git a/tests/Utilities/ImageAssetTest.php b/tests/Utilities/ImageAssetTest.php
new file mode 100644
index 0000000..7965d34
--- /dev/null
+++ b/tests/Utilities/ImageAssetTest.php
@@ -0,0 +1,66 @@
+<?php
+declare(strict_types=1);
+
+namespace Assets\Test\Utilities;
+
+use Assets\Utilities\ImageAsset;
+use Cake\TestSuite\TestCase;
+
+class ImageAssetTest extends TestCase
+{
+    protected const DATA_IMAGES = __DIR__ . DS;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        if (!defined('PLUGIN_ROOT')) {
+            include __DIR__ . DS . '..' . DS . 'bootstrap.php';
+        }
+    }
+
+    public function testCreateFromPathWithInvalidPath(): void
+    {
+        static::expectException(\InvalidArgumentException::class);
+        $image = ImageAsset::createFromPath('invalid-path');
+    }
+
+    public function testCreateFromPathWithValidPath(): void
+    {
+        $path = static::DATA_IMAGES . 'cake.jpg';
+        $image = ImageAsset::createFromPath($path);
+        static::assertInstanceOf(ImageAsset::class, $image);
+
+        $renderedPath = WWW_ROOT . $image->toWebp()->scaleWidth(120)->getPath();
+        static::assertFileExists($renderedPath);
+        $splFileInfo = new \SplFileInfo($renderedPath);
+        static::assertEquals('image/webp', mime_content_type($renderedPath));
+        static::assertEquals(6178, $splFileInfo->getSize());
+
+        $renderedPathOfLargeJpg = WWW_ROOT . $image->toJpg()->scaleWidth(240)->getPath();
+        static::assertFileExists($renderedPathOfLargeJpg);
+        $splFileInfoJpg = new \SplFileInfo($renderedPathOfLargeJpg);
+        static::assertEquals('image/jpeg', mime_content_type($renderedPathOfLargeJpg));
+        static::assertEquals(22336, $splFileInfoJpg->getSize());
+    }
+
+    public function testHtmlCreation(): void
+    {
+        $path = static::DATA_IMAGES . 'cake.jpg';
+        $image = ImageAsset::createFromPath($path);
+        static::assertInstanceOf(ImageAsset::class, $image);
+
+        $html = $image
+            ->scaleWidth(230)
+            ->setCSS('some-css')
+            ->setLazyLoading(false)
+            ->getHTML([
+                'data-test' => 123,
+            ]);
+
+        static::assertNotEmpty($html);
+        static::assertStringContainsString('width="230"', $html);
+        static::assertStringContainsString('class="some-css"', $html);
+        static::assertStringContainsString('data-test="123"', $html);
+        static::assertStringContainsString('loading="eager"', $html);
+    }
+}
diff --git a/tests/Utilities/cake.jpg b/tests/Utilities/cake.jpg
new file mode 100644
index 0000000..a3800ce
Binary files /dev/null and b/tests/Utilities/cake.jpg differ