diff --git a/core/modules/image/image.test b/core/modules/image/image.test
index a29b4f3..2ab23ea 100644
--- a/core/modules/image/image.test
+++ b/core/modules/image/image.test
@@ -1128,4 +1128,53 @@ class ImageDimensionsUnitTest extends DrupalWebTestCase {
     $img_tag = theme_image_style($variables);
     $this->assertEqual($img_tag, '<img typeof="foaf:Image" src="' . $url . '" alt="" />', t('Expected img tag was found.'));
   }
+  
+  /**
+   * Tests the image_scale_dimensions (and consequently
+   * image_dimensions_scale()) functions to return correct values.
+   */
+  function testScaleDimensionsEffect() {
+    // Scale an image to be 320 pixels wide.
+    $data = array(
+      'width' => 320,
+      'height' => NULL,
+      'upscale' => TRUE,
+    );
+
+    // Large landscape image scaled down.
+    $dimensions = array(
+      'width' => 640,
+      'height' => 480,
+    );
+    image_scale_dimensions($dimensions, $data);
+    $this->assertEqual(320, $dimensions['width'], t('Width for the landscape dimensions have scaled down correctly.'));
+    $this->assertEqual(240, $dimensions['height'], t('Height for the landscape dimensions have scaled down correctly.'));
+
+    // Large portrait image scaled down.
+    $dimensions = array(
+      'width' => 640,
+      'height' => 1280,
+    );
+    image_scale_dimensions($dimensions, $data);
+    $this->assertEqual(320, $dimensions['width'], t('Width for the portrait dimensions have scaled down correctly.'));
+    $this->assertEqual(640, $dimensions['height'], t('Height for the portrait dimensions have scaled down correctly.'));
+    
+    // Small landscape image upscaled.
+    $dimensions = array(
+      'width' => 160,
+      'height' => 120,
+    );
+    image_scale_dimensions($dimensions, $data);
+    $this->assertEqual(320, $dimensions['width'], t('Width for the landscape dimensions have scaled up correctly.'));
+    $this->assertEqual(240, $dimensions['height'], t('Height for the landscape dimensions have scaled up correctly.'));
+
+    // Small portrait image upscaled.
+    $dimensions = array(
+      'width' => 160,
+      'height' => 320,
+    );
+    image_scale_dimensions($dimensions, $data);
+    $this->assertEqual(320, $dimensions['width'], t('Width for the portrait dimensions have scaled up correctly.'));
+    $this->assertEqual(640, $dimensions['height'], t('Height for the portrait dimensions have scaled up correctly.'));
+  }
 }