Add typical arg dsl test for documentation
The `,` case is probably the most common separator used, so explicitly
ensure and protect its behavior. This also acts as documentation.
@@ -93,6 +93,7 @@ class TestArgsDSL(_BaseTestCase):
('--a ', {'a': 'foo'}, ['--a', 'foo']),
('--a ', {'a': ['foo']}, ['--a', 'foo']),
('--a ', {'a': ['foo', 'bar']}, ['--a', 'foo bar']),
+ ('--a,', {'a': ['foo', 'bar']}, ['--a', 'foo,bar']),
('@a ', {'a': 'foo'}, ['foo']),
('@a ', {'a': ['foo']}, ['foo']),
('@a ', {'a': ['foo', 'bar']}, ['foo bar']),
