finalize

type Command interface {
	Run(*exec.Cmd) error
}

type Finalizer struct {
	Stager           Stager
	Versions         Versions
	Log              *libbuildpack.Logger
	Command          Command
	Gem12Factor      bool
	GemStaticAssets  bool
	GemStdoutLogging bool
	RailsVersion     int
}

type Stager interface {
	BuildDir() string
	DepsIdx() string
	DepDir() string
}

type Versions interface {
	HasGem(string) (bool, error)
	GemMajorVersion(string) (int, error)
	HasGemVersion(string, ...string) (bool, error)
}