test

type Flow interface {
	// PushErrorHandler only pushes a stopFunc
	PushErrorHandler(StopFunc) Flow

	// Run calls the startFunc and expects no error returned.
	// If a non-nil error is returned or panic, shutdown must be called at once.
	// The error will be stored and thus could be checked by the caller later.
	Run(context.Context, StartFunc, StopFunc) Flow

	// RunWithoutSideEffect calls the startFunc and does not expect any side effects from it.
	// If a non-nil error is returned or panic, shutdown must be called at once.
	// The error will be stored and thus could be checked by the caller later.
	RunWithoutSideEffect(context.Context, StartFunc) Flow

	// Shutdown does not actually shutdown the flow,
	// but only returns a function containing all stopFunc(s) to be executed.
	// The timing to do the real shutdown can be determined by users.
	Shutdown() StopFunc

	// Error returns all errors returned from startFunc(s)
	// Nil error imply a successful flow.
	Error() error
}

type StartFunc func() error

type StopFunc func()