Fix min_constraint bug in _parse_range

Resolve #1389

Author: iimog

src/torchio/transforms/transform.py

@@ -331,7 +331,7 @@ def _parse_range(
                         f'If {name} is a single number, it must be of'
                         f' type {type_constraint}, not {nums_range}',
                     )
-            min_range = -nums_range if min_constraint is None else nums_range
+            min_range = -nums_range if min_constraint is None else min_constraint
             return (min_range, nums_range)
 
         try:

tests/transforms/test_transforms.py

@@ -255,7 +255,7 @@ def test_arguments_are_and_are_not_dict(self):
 
     def test_min_constraint(self):
         transform = tio.RandomNoise()
-        assert transform._parse_range(3, 'name', min_constraint=0) == (0,3)
+        assert transform._parse_range(3, 'name', min_constraint=0) == (0, 3)
 
     def test_bad_over_max(self):
         transform = tio.RandomNoise()