added Image::basePath()

src/Intervention/Image/Image.php

@@ -79,7 +79,14 @@ class Image extends File
      */
     public function save($path = null, $quality = null)
     {
-        $path = is_null($path) ? ($this->dirname .'/'. $this->basename) : $path;
+        $path = is_null($path) ? $this->basePath() : $path;
+
+        if (is_null($path)) {
+            throw new Exception\NotWritableException(
+                "Can't write to undefined path."
+            );
+        }
+
         $data = $this->encode(pathinfo($path, PATHINFO_EXTENSION), $quality);
         $saved = @file_put_contents($path, $data);
 
@@ -253,6 +260,20 @@ class Image extends File
         return $this->mime;
     }
 
+    /**
+     * Get fully qualified path to image
+     *
+     * @return string
+     */
+    public function basePath()
+    {
+        if ($this->dirname && $this->basename) {
+            return ($this->dirname .'/'. $this->basename);
+        }
+
+        return null;
+    }
+
     /**
      * Returns encoded image data in string conversion
      *

tests/ImageTest.php

@@ -57,6 +57,12 @@ class ImageTest extends PHPUnit_Framework_TestCase
         $this->assertEquals('image/png', $image->mime());
     }
 
+    public function testBasePath()
+    {
+        $image = $this->getTestImage();
+        $this->assertEquals('./tmp/foo.png', $image->basePath());
+    }
+
     private function getTestImage()
     {
         $size = Mockery::mock('\Intervention\Image\Size', array(800, 600));
@@ -67,6 +73,8 @@ class ImageTest extends PHPUnit_Framework_TestCase
         $driver->shouldReceive('executeCommand')->andReturn($command);
         $image = new Image($driver, 'mock');
         $image->mime = 'image/png';
+        $image->dirname = './tmp';
+        $image->basename = 'foo.png';
 
         return $image;
     }