Added test for save image in utils (#847)

test/test_utils.py

+import os
 import torch
 import torchvision.utils as utils
 import unittest
@@ -35,6 +36,13 @@ class Tester(unittest.TestCase):
         assert torch.equal(norm_max, rounded_grid_max), 'Normalized max is not equal to 1'
         assert torch.equal(norm_min, rounded_grid_min), 'Normalized min is not equal to 0'
 
+    def test_save_image(self):
+        t = torch.rand(2, 3, 64, 64)
+        file_name = 'test_image.png'
+        utils.save_image(t, file_name)
+        assert os.path.exists(file_name), 'The image is not present after save'
+        os.remove(file_name)
+
 
 if __name__ == '__main__':
     unittest.main()