def validate_instance(instance, validators, test_only=False, **kwargs):
    """Runs all validators against the specified instance.

    :param instance: An instance to validate.
    :param validators: A sequence of ImageValidators.
    :param test_only: If true, all validators will only verify that a
        desired state is present, and fail if it is not. If false, all
        validators will attempt to enforce the desired state if possible,
        and succeed if this enforcement succeeds.
    :raises ImageValidationError: If validation fails.
    """
    with instance.remote() as remote:
        for validator in validators:
            validator.validate(remote, test_only=test_only, **kwargs)
