refine error message of randint (#25613)

python/paddle/fluid/tests/unittests/test_randint_op.py

@@ -57,6 +57,7 @@ class TestRandintOpError(unittest.TestCase):
             self.assertRaises(TypeError, paddle.randint, 5, shape=np.array([2]))
             self.assertRaises(TypeError, paddle.randint, 5, dtype='float32')
             self.assertRaises(ValueError, paddle.randint, 5, 5)
+            self.assertRaises(ValueError, paddle.randint, -5)
 
 
 class TestRandintOp_attr_tensorlist(OpTest):

python/paddle/tensor/random.py

@@ -114,6 +114,10 @@ def randint(low=0, high=None, shape=[1], dtype=None, name=None):
 
     """
     if high is None:
+        if low <= 0:
+            raise ValueError(
+                "If high is None, low must be greater than 0, but received low = {0}.".
+                format(low))
         high = low
         low = 0
     if dtype is None: