Fix Faker.random_number intermittent exceptions #1074 (#1089)

* ensure max number of digits generated in random_number is > -1 when param is not passed and > 0 when fix_len is True

* add additional tests for random_number functionality

faker/providers/__init__.py

@@ -151,10 +151,15 @@ def random_number(self, digits=None, fix_len=False):
             fixed length number
         """
         if digits is None:
-            digits = self.random_digit()
+            digits = self.random_digit_not_null()
+        if digits < 0:
+            raise ValueError("The digit parameter must be greater than or equal to 0.")
         if fix_len:
-            return self.generator.random.randint(
-                pow(10, digits - 1), pow(10, digits) - 1)
+            if digits > 0:
+                return self.generator.random.randint(
+                    pow(10, digits - 1), pow(10, digits) - 1)
+            else:
+                raise ValueError("A number of fixed length cannot have less than 1 digit in it.")
         else:
             return self.generator.random.randint(0, pow(10, digits) - 1)
 

tests/test_factory.py

@@ -912,6 +912,14 @@ def test_random_number(self):
         number = provider.random_number(10, True)
         assert len(str(number)) == 10
 
+        # Digits parameter < 0
+        with self.assertRaises(ValueError):
+            number = provider.random_number(-1, True)
+
+        # Digits parameter < 1 with fix_len=True
+        with self.assertRaises(ValueError):
+            number = provider.random_number(0, True)
+
     def test_instance_seed_chain(self):
         factory = Factory.create()