def test_append_header():
response = Response()
response.set_header('x-test', 'foo')
headers = [value for name, value in response.headerlist
if name.title() == 'X-Test']
assert ['foo'] == headers
assert 'foo' == response['x-test']
response.add_header('X-Test', 'bar')
headers = [value for name, value in response.headerlist
if name.title() == 'X-Test']
assert ['foo', 'bar'] == headers
assert 'foo' == response['x-test']
