Added unitests for nagetive cases.

tests/python/unittest/test_image.py

@@ -23,6 +23,8 @@
 import tempfile
 import unittest
 
+from builtins import bytearray
+
 from nose.tools import raises
 
 def _get_data(url, dirname):
@@ -92,6 +94,26 @@ def test_imdecode(self):
             cv_image = cv2.imread(img)
             assert_almost_equal(image.asnumpy(), cv_image)
 
+    def test_imdecode_bytearray(self):
+        try:
+            import cv2
+        except ImportError:
+            return
+        for img in TestImage.IMAGES:
+            with open(img, 'rb') as fp:
+                str_image = bytearray(fp.read())
+                image = mx.image.imdecode(str_image, to_rgb=0)
+            cv_image = cv2.imread(img)
+            assert_almost_equal(image.asnumpy(), cv_image)
+
+    @raises(ValueError)
+    def test_imdecode_empty_buffer(self):
+        try:
+            import cv2
+        except ImportError:
+            raise ValueError("cv2 is not installed")
+        mx.image.imdecode(b'', to_rgb=0)
+
     def test_scale_down(self):
         assert mx.image.scale_down((640, 480), (720, 120)) == (640, 106)
         assert mx.image.scale_down((360, 1000), (480, 500)) == (360, 375)