Do not separate run/main methods

This complication is unnecessary.

tests/e2e_tests.py

@@ -12,17 +12,17 @@
 @mock.patch('tzupdate.link_localtime')
 def test_end_to_end_no_args(link_localtime_mock, get_timezone_for_ip_mock):
     get_timezone_for_ip_mock.return_value = FAKE_TIMEZONE
-    args = tzupdate.parse_args([])
-    tzupdate.run(args)
+    args = []
+    tzupdate.main(args)
     assert_true(link_localtime_mock.called)
 
 
 @mock.patch('tzupdate.get_timezone_for_ip')
 @mock.patch('tzupdate.link_localtime')
 def test_print_only_no_link(link_localtime_mock, get_timezone_for_ip_mock):
     get_timezone_for_ip_mock.return_value = FAKE_TIMEZONE
-    args = tzupdate.parse_args(['-p'])
-    tzupdate.run(args)
+    args = ['-p']
+    tzupdate.main(args)
     assert_false(link_localtime_mock.called)
 
 
@@ -32,8 +32,8 @@ def test_explicit_paths(link_localtime_mock, get_timezone_for_ip_mock):
     localtime_path = '/l'
     zoneinfo_path = '/z'
     get_timezone_for_ip_mock.return_value = FAKE_TIMEZONE
-    args = tzupdate.parse_args(['-l', localtime_path, '-z', zoneinfo_path])
-    tzupdate.run(args)
+    args = ['-l', localtime_path, '-z', zoneinfo_path]
+    tzupdate.main(args)
     assert_true(
         link_localtime_mock.called_once_with(
             FAKE_TIMEZONE, zoneinfo_path, localtime_path,
@@ -46,15 +46,16 @@ def test_explicit_paths(link_localtime_mock, get_timezone_for_ip_mock):
 def test_explicit_ip(_, get_timezone_for_ip_mock):
     ip_addr = '1.2.3.4'
     get_timezone_for_ip_mock.return_value = FAKE_TIMEZONE
-    args = tzupdate.parse_args(['-a', ip_addr])
-    tzupdate.run(args)
+    args = ['-a', ip_addr]
+    tzupdate.main(args)
     assert_true(get_timezone_for_ip_mock.called_once_with(ip_addr))
 
+
 @mock.patch('tzupdate.link_localtime')
 def test_explicit_timezone(link_localtime_mock):
     timezone = 'Foo/Bar'
-    args = tzupdate.parse_args(['-t', timezone])
-    tzupdate.run(args)
+    args = ['-t', timezone]
+    tzupdate.main(args)
     assert_true(
         link_localtime_mock.called_once_with(
             timezone,

tzupdate.py

@@ -143,7 +143,13 @@ def parse_args(argv):
     return args
 
 
-def run(args):
+def main(argv=None):
+    if argv is None:
+        argv = sys.argv[1:]
+
+    args = parse_args(argv)
+    logging.basicConfig(level=args.log_level)
+
     if args.timezone:
         timezone = args.timezone
         print('Using explicitly passed timezone: %s' % timezone)
@@ -158,23 +164,5 @@ def run(args):
         print('Linked %s to %s.' % (args.localtime_path, zoneinfo_tz_path))
 
 
-def main(argv=None):
-    if argv is None:
-        argv = sys.argv[1:]
-
-    args = parse_args(argv)
-    logging.basicConfig(level=args.log_level)
-
-    try:
-        run(args)
-    except TimezoneUpdateException as thrown_exc:
-        if args.log_level == logging.DEBUG:
-            # Give the full traceback if we are in debug mode
-            raise
-        else:
-            print('fatal: {0!s}'.format(thrown_exc), file=sys.stderr)
-            sys.exit(thrown_exc.exit_code)
-
-
 if __name__ == '__main__':
     main()