Bail out if the name of the local timezone cannot be determined

2 files changed, 12 insertions, 0 deletions

diff --git a/apscheduler/util.py b/apscheduler/util.py
index 8504ac0..1544910 100644
--- a/apscheduler/util.py
+++ b/apscheduler/util.py
@@ -76,6 +76,8 @@ def astimezone(obj):
     if isinstance(obj, tzinfo):
         if not hasattr(obj, 'localize') or not hasattr(obj, 'normalize'):
             raise TypeError('Only timezones from the pytz library are supported')
+        if obj.zone == 'local':
+            raise ValueError('Unable to determine the name of the local timezone -- use an explicit timezone instead')
         return obj
     if obj is not None:
         raise TypeError('Expected tzinfo, got %s instead' % obj.__class__.__name__)
diff --git a/tests/test_util.py b/tests/test_util.py
index bf13476..d454f10 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -12,6 +12,11 @@ from apscheduler.util import (
     datetime_repr, repr_escape)
 from tests.conftest import minpython, maxpython
 
+try:
+    from unittest.mock import Mock
+except ImportError:
+    from mock import Mock
+
 
 class DummyClass(object):
     def meth(self):
@@ -78,6 +83,11 @@ class TestAstimezone(object):
         exc = pytest.raises(TypeError, astimezone, tzinfo())
         assert 'Only timezones from the pytz library are supported' in str(exc.value)
 
+    def test_bad_local_timezone(self):
+        zone = Mock(tzinfo, localize=None, normalize=None, zone='local')
+        exc = pytest.raises(ValueError, astimezone, zone)
+        assert 'Unable to determine the name of the local timezone' in str(exc.value)
+
     def test_bad_value(self):
         exc = pytest.raises(TypeError, astimezone, 4)
         assert 'Expected tzinfo, got int instead' in str(exc.value)