Add support for auto resize

src/Transformation/Resize/Crop/CropTrait.php

@@ -51,6 +51,24 @@ public static function thumbnail($width = null, $height = null, $gravity = null,
         return static::createCrop(CropMode::THUMBNAIL, $width, $height, $gravity, $x, $y);
     }
 
+    /**
+     * Automatically determines the best crop based on the gravity and specified dimensions.
+     *
+     * If the requested dimensions are smaller than the best crop, the result is downscaled.
+     * If the requested dimensions are larger than the original image, the result is upscaled.
+     * Use this mode in conjunction with the g (gravity) parameter.
+     *
+     * @param int|float|string|null $width   The required width of a transformed asset.
+     * @param int|float|null        $height  The required height of a transformed asset.
+     * @param Gravity               $gravity Which part of the original image to include.
+     *
+     * @return Crop
+     */
+    public static function auto($width = null, $height = null, $gravity = null)
+    {
+        return static::createCrop(CropMode::AUTO, $width, $height, $gravity);
+    }
+
     /**
      * Creates Crop instance.
      *

src/Transformation/Resize/Parameter/CropMode.php

@@ -120,6 +120,11 @@ class CropMode extends BaseQualifier
      */
     const THUMBNAIL = 'thumb';
 
+    /**
+     * The AUTO crop mode automatically determines the best crop based on the gravity and specified dimensions.
+     */
+    const AUTO = 'auto';
+
     /**
      * The IMAGGA_CROP crop mode crops your image based on automatically calculated areas of interest within each
      * specific photo.

tests/Unit/Transformation/Image/ResizeTest.php

@@ -10,6 +10,7 @@
 
 namespace Cloudinary\Test\Unit\Transformation\Image;
 
+use Cloudinary\Test\TransformationTestCase;
 use Cloudinary\Transformation\Argument\Color;
 use Cloudinary\Transformation\AspectRatio;
 use Cloudinary\Transformation\AutoGravity;
@@ -25,12 +26,11 @@
 use Cloudinary\Transformation\ResizeMode;
 use Cloudinary\Transformation\Scale;
 use InvalidArgumentException;
-use PHPUnit\Framework\TestCase;
 
 /**
  * Class ResizeTest
  */
-final class ResizeTest extends TestCase
+final class ResizeTest extends TransformationTestCase
 {
     public function testScale()
     {
@@ -238,6 +238,21 @@ public function testCrop()
             'c_thumb,g_auto,h_200,w_100,z_0.5',
             (string)$thumb
         );
+
+        self::assertStrEquals(
+            'c_auto,g_auto,h_200,w_100',
+            Crop::auto(100, 200, Gravity::auto())
+        );
+
+        self::assertStrEquals(
+            'c_auto,g_auto,h_200,w_100',
+            Crop::auto()->width(100)->height(200)->gravity(Gravity::auto())
+        );
+
+        self::assertStrEquals(
+            'ar_0.5,c_auto,g_auto',
+            Crop::auto()->gravity(Gravity::auto())->aspectRatio(0.5)
+        );
     }
 
     public function testResize()