public void WithCredentials_throws_argumentException_for_invalid_args()
{
var config = new ClusterOptions();
Assert.Throws <ArgumentException>(() => config.Credentials(null, null));
Assert.Throws <ArgumentException>(() => config.Credentials(string.Empty, null));
Assert.Throws <ArgumentException>(() => config.Credentials(null, string.Empty));
Assert.Throws <ArgumentException>(() => config.Credentials(string.Empty, string.Empty));
}