Fix enum derivation

[wordrak]

Fix enum derivation when the enum composed of case objects but they are not within another class

[yanns]

@wordrak thanks a lot for the PR. To help me reviewing this, could you explain more what the actual issue is?

[wordrak]

Hi, issue is that the deriveEnumType macro fails when the Enum is a "case object hierarchy" and it is not contained in another object.

e.g.:

  sealed trait Fruit

  case object RedApple extends Fruit
  case object SuperBanana extends Fruit
  case object MegaOrange extends Fruit
  
  object Fruit {
    implicit val enumType = deriveEnumType[Fruit]()
  }

If you revert the changes in the TestCase then you see the problem.

[yanns]

instead of creating the term derive.SuperBanana that is failing:

[error] /Users/yannsimon/projects/sangria-graphql/sangria/modules/derivation/src/test/scala/sangria/macros/derive/DeriveEnumTypeMacroSpec.scala:55:48: not found: value derive
[error]       val singletonEnum = deriveEnumType[Fruit]()
[error]                                                ^

we now create the term SuperBanana.

[yanns]

Thanks a lot!