From 9ff5cab8b1fce5bf860ac9780402adedea0e8b44 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@gmail.com>
Date: Thu, 29 Dec 2016 11:28:58 +1100
Subject: [PATCH] Added test

---
 Tests/test_file_gif.py | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/Tests/test_file_gif.py b/Tests/test_file_gif.py
index 94a8ea92c..75aafbc72 100644
--- a/Tests/test_file_gif.py
+++ b/Tests/test_file_gif.py
@@ -56,7 +56,7 @@ class TestFileGif(PillowTestCase):
         # 256 color Palette image, posterize to > 128 and < 128 levels
         # Size bigger and smaller than 512x512
         # Check the palette for number of colors allocated.
-        # Check for correctness after conversion back to RGB        
+        # Check for correctness after conversion back to RGB
         def check(colors, size, expected_palette_length):
             # make an image with empty colors in the start of the palette range
             im = Image.frombytes('P', (colors,colors),
@@ -70,7 +70,7 @@ class TestFileGif(PillowTestCase):
             # check palette length
             palette_length = max(i+1 for i,v in enumerate(reloaded.histogram()) if v)
             self.assertEqual(expected_palette_length, palette_length)
-            
+
             self.assert_image_equal(im.convert('RGB'), reloaded.convert('RGB'))
 
 
@@ -288,7 +288,7 @@ class TestFileGif(PillowTestCase):
         im_list = [
             Image.new('L', (100, 100), '#000'),
             Image.new('L', (100, 100), '#111'),
-            Image.new('L', (100, 100), '#222'),
+            Image.new('L', (100, 100), '#222')
         ]
 
         #duration as list
@@ -323,7 +323,31 @@ class TestFileGif(PillowTestCase):
             except EOFError:
                 pass
 
+    def test_identical_frames(self):
+        duration_list = [1000, 1500, 2000, 4000]
 
+        out = self.tempfile('temp.gif')
+        im_list = [
+            Image.new('L', (100, 100), '#000'),
+            Image.new('L', (100, 100), '#000'),
+            Image.new('L', (100, 100), '#000'),
+            Image.new('L', (100, 100), '#111')
+        ]
+
+        #duration as list
+        im_list[0].save(
+            out,
+            save_all=True,
+            append_images=im_list[1:],
+            duration=duration_list
+        )
+        reread = Image.open(out)
+
+        # Assert that the first three frames were combined
+        self.assertEqual(reread.n_frames, 2)
+
+        # Assert that the new duration is the total of the identical frames
+        self.assertEqual(reread.info['duration'], 4500)
 
     def test_number_of_loops(self):
         number_of_loops = 2
@@ -427,7 +451,7 @@ class TestFileGif(PillowTestCase):
         reloaded = Image.open(out)
 
         self.assertEqual(reloaded.info['transparency'], 253)
-        
+
 
 if __name__ == '__main__':
     unittest.main()