def test_hostname_validation_failure_too_long():
"""
Test function returns False if a hostname over 255 chars is specified
"""
long_hostname = 'x' * 256
assert not valid_hostnames(['example.com', long_hostname])
def test_hostname_validation_failure_with_leading_hyphen():
"""
Test function returns False if a hostname with a leading hyphen is specified
"""
assert not valid_hostnames(['example.com', '-example'])
def test_hostname_validation_success():
"""
Test function returns True if valid hostnames are specified
"""
assert valid_hostnames(['example.com', 'example'])
