added checksumCommand

src/Intervention/Image/Commands/ChecksumCommand.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Intervention\Image\Commands;
+
+class ChecksumCommand extends AbstractCommand
+{
+    public function execute($image)
+    {
+        $colors = array();
+
+        $size = $image->getSize();
+
+        for ($x=0; $x <= ($size->width-1); $x++) {
+            for ($y=0; $y <= ($size->height-1); $y++) {
+                $colors[] = $image->pickColor($x, $y, 'array');
+            }
+        }
+
+        $this->setOutput(md5(serialize($colors)));
+
+        return true;
+    }
+}

tests/ChecksumCommandTest.php

@@ -0,0 +1,26 @@
+<?php
+
+use Intervention\Image\Commands\ChecksumCommand;
+
+class ExifCommandTest extends PHPUnit_Framework_TestCase
+{
+    public function tearDown()
+    {
+        Mockery::close();
+    }
+    
+    public function testExecute()
+    {
+        $size = Mockery::mock('Intervention\Image\Size', array(3, 3));
+        $color = array(0,0,0,1);
+        $resource = imagecreatefrompng(__DIR__.'/images/tile.png');
+        $image = Mockery::mock('Intervention\Image\Image');
+        $image->shouldReceive('getSize')->once()->andReturn($size);
+        $image->shouldReceive('pickColor')->times(9)->andReturn($color);
+        $command = new ChecksumCommand(array());
+        $result = $command->execute($image);
+        $this->assertTrue($result);
+        $this->assertTrue($command->hasOutput());
+        $this->assertEquals('ec9cbdb71be04e26b4a89333f20c273b', $command->getOutput());
+    }
+}