!1806 Add crop size check to python RandomCrop op

Merge pull request !1806 from Tinazhang/random-crop-error-msg

mindspore/dataset/transforms/vision/py_transforms_util.py

@@ -455,6 +455,9 @@ def random_crop(img, size, padding, pad_if_needed, fill_value, padding_mode):
     def _input_to_factor(img, size):
         img_width, img_height = img.size
         height, width = size
+        if height > img_height or width > img_width:
+            raise ValueError("Crop size {} is larger than input image size {}".format(size, (img_height, img_width)))
+
         if width == img_width and height == img_height:
             return 0, 0, img_height, img_width
 

tests/ut/python/dataset/test_random_crop.py

@@ -280,6 +280,7 @@ def test_random_crop_04_py():
         data.create_dict_iterator().get_next()
     except RuntimeError as e:
         logger.info("Got an exception in DE: {}".format(str(e)))
+        assert "Crop size" in str(e)
 
 def test_random_crop_05_c():
     """