Add Generator interface

[klnusbaum]

In certain cases (namely testing) a person may want to deterministically generate UUIDs. There currently aren't many facilities in this UUID library for doing this.

I propose introducing a new interface called Generator. A Generator has all of the standard uuid creation functions on it, but has the advantage of being able to be mocked. Developers wishing to write more testable code can write code that instead of directly using the creation function, instead uses some instance of the Generator interface. For the code they actually want to run, they can inject the Generator returned by the NewGenerator function. When they want to test, they can inject a mocked Generator of their choice (using mockgen, mockery, or their own custom implementation) and deterministically control what UUIDs are generated.

For instance, consider the following generator that might be used for testing. In this case, the author only cares about deterministically generating a certain sequence of V4 UUIDS.

type MyTestGen struct {
  Sequence []satori.UUID
  Iter            int
}

func (_ MyTestGen) NewV1() satori.UUID{return  satori.Nil}
func (_ MyTestGen) NewV2(domain byte) satori.UUID{return  satori.Nil}
func (_ MyTestGen) NewV3(ns UUID, name string) satori.UUID{return  satori.Nil}
func (m MyTestGen) NewV4() satori.UUID{
  toReturn := m.Sequence[m.Iter]
  m.Iter += 1
  return toReturn
}
func (_ MyTestGen) NewV5(ns UUID, name string) satori.UUID{return  satori.Nil}

[coveralls]

Coverage increased (+0.1%) to 96.667% when pulling 9a63855 on klnusbaum:generator into 5bf94b6 on satori:master.

[coveralls]

Coverage increased (+0.1%) to 96.667% when pulling c459c6c on klnusbaum:generator into 5bf94b6 on satori:master.

[coveralls]

Coverage increased (+0.1%) to 96.667% when pulling c459c6c on klnusbaum:generator into 5bf94b6 on satori:master.

[coveralls]

Coverage increased (+0.1%) to 96.667% when pulling db9933c on klnusbaum:generator into 5bf94b6 on satori:master.

[bufdev]

typo: of

[bufdev]

typo: domain

[coveralls]

Coverage increased (+0.1%) to 96.667% when pulling 2b4c18d on klnusbaum:generator into 5bf94b6 on satori:master.

[satori]

This PR was superseded by #62