Better error handling

This fixes #34

2 files changed, 8 insertions, 2 deletions

diff --git a/src/croniter/croniter.py b/src/croniter/croniter.py
index af3130f..a461bbf 100644
--- a/src/croniter/croniter.py
+++ b/src/croniter/croniter.py
@@ -3,6 +3,7 @@
 
 from __future__ import absolute_import, print_function, division
 
+import traceback as _traceback
 import copy
 import math
 import re
@@ -785,13 +786,14 @@ class croniter(object):
         """Shallow non Croniter ValueError inside a nice CroniterBadCronError"""
         try:
             return cls._expand(expr_format, hash_id=hash_id)
-        except ValueError as exc:
+        except (ValueError,) as exc:
             error_type, error_instance, traceback = sys.exc_info()
             if isinstance(exc, CroniterError):
                 raise
             if int(sys.version[0]) >= 3:
+                trace = _traceback.format_exc()
                 globs, locs = _get_caller_globals_and_locals()
-                exec("raise CroniterBadCronError from  exc", globs, locs)
+                raise CroniterBadCronError(trace)
             else:
                 raise CroniterBadCronError("{0}".format(exc))
 
diff --git a/src/croniter/tests/test_croniter.py b/src/croniter/tests/test_croniter.py
index a9d8ade..3eecfd2 100755
--- a/src/croniter/tests/test_croniter.py
+++ b/src/croniter/tests/test_croniter.py
@@ -1473,6 +1473,10 @@ class CroniterTest(base.TestCase):
 
         self.assertEqual(n1, datetime_to_timestamp(base) + 60)
 
+    def test_issue_k34(self):
+        # invalid cron, but should throw appropriate exception
+        self.assertRaises(CroniterBadCronError, croniter, "4 0 L/2 2 0")
+
     def test_issue_k33(self):
         y = 2018
         # At 11:30 PM, between day 1 and 7 of the month, Monday through Friday, only in January