Fix ZeroDivisionError with "* * R/0 * *"

2 files changed, 12 insertions, 2 deletions

diff --git a/src/croniter/croniter.py b/src/croniter/croniter.py
index 3890c4e..0d3324e 100644
--- a/src/croniter/croniter.py
+++ b/src/croniter/croniter.py
@@ -851,7 +851,12 @@ class HashExpander:
             crc = random.randint(0, 0xFFFFFFFF)
         else:
             crc = binascii.crc32(hash_id) & 0xFFFFFFFF
-        return ((crc >> idx) % (range_end - range_begin + 1)) + range_begin
+
+        rng = range_end - range_begin + 1
+        if rng == 0:
+            raise CroniterBadCronError("Bad range")
+
+        return ((crc >> idx) % rng) + range_begin
 
     def match(self, efl, idx, expr, hash_id=None, **kw):
         return hash_expression_re.match(expr)
diff --git a/src/croniter/tests/test_croniter_hash.py b/src/croniter/tests/test_croniter_hash.py
index 88f228e..084a3af 100644
--- a/src/croniter/tests/test_croniter_hash.py
+++ b/src/croniter/tests/test_croniter_hash.py
@@ -1,6 +1,6 @@
 from datetime import datetime, timedelta
 
-from croniter import croniter, CroniterNotAlphaError
+from croniter import croniter, CroniterNotAlphaError, CroniterBadCronError
 from croniter.tests import base
 
 
@@ -122,6 +122,11 @@ class CroniterHashTest(CroniterHashBase):
         with self.assertRaises(TypeError):
             croniter('H H * * *', self.epoch, hash_id={1: 2})
 
+    def test_invalid_divisor(self):
+        """Test an invalid divisor type raises CroniterBadCronError"""
+        with self.assertRaises(CroniterBadCronError):
+            croniter('* * H/0 * *', self.epoch, hash_id=self.hash_id)
+
 
 class CroniterWordAliasTest(CroniterHashBase):
     def test_hash_word_midnight(self):