Added a unit test for steganlysis-parity

stegano/steganalysis/parity.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-#-*- coding: utf-8 -*-
+# -*- coding: utf-8 -*-
 
 # Stegano - Stegano is a basic Python Steganography module.
 # Copyright (C) 2010-2019  Cédric Bonhomme - https://www.cedricbonhomme.org
@@ -26,16 +26,16 @@ __license__ = "GPLv3"
 
 from PIL import Image
 
-def steganalyse(img):
+
+def steganalyse(img: Image.Image) -> Image.Image:
     """
     Steganlysis of the LSB technique.
     """
-    encoded = img.copy()
+    encoded: Image.Image = img.copy()
     width, height = img.size
-    bits = ""
     for row in range(height):
         for col in range(width):
-            r, g, b = img.getpixel((col, row))
+            r, g, b = img.getpixel((col, row))[0:3]
             if r % 2 == 0:
                 r = 0
             else:
@@ -48,5 +48,5 @@ def steganalyse(img):
                 b = 0
             else:
                 b = 255
-            encoded.putpixel((col, row), (r, g , b))
+            encoded.putpixel((col, row), (r, g, b))
     return encoded

tests/test_steganalysis.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Stéganô - Stéganô is a basic Python Steganography module.
+# Copyright (C) 2010-2017  Cédric Bonhomme - https://www.cedricbonhomme.org
+#
+# For more information : https://github.com/cedricbonhomme/Stegano
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>
+
+__author__ = "Cedric Bonhomme"
+__version__ = "$Revision: 0.9.4 $"
+__date__ = "$Date: 2019/06/06 $"
+__revision__ = "$Date: 2019/06/06 $"
+__license__ = "GPLv3"
+
+import io
+import os
+import base64
+import unittest
+from unittest.mock import patch
+
+from stegano import lsb
+from stegano.steganalysis import parity
+from PIL import Image, ImageChops
+
+
+class TestSteganalysis(unittest.TestCase):
+
+    def test_parity(self):
+        """Test stegano.steganalysis.parity
+        """
+        text_file_to_hide = './tests/sample-files/lorem_ipsum.txt'
+        with open(text_file_to_hide) as f:
+            message = f.read()
+        secret = lsb.hide("./tests/sample-files/Lenna.png", message)
+        analysis = parity.steganalyse(secret)
+        target = Image.open("./tests/expected-results/parity.png")
+        diff = ImageChops.difference(target, analysis).getbbox()
+        self.assertTrue(diff is None)
+
+
+if __name__ == '__main__':
+    unittest.main()