Add basic support for fragments

[felipecsl]

• Added basic fragment support, as documented on Add DESIGN.md with discussion of the mapping design #15. It's the same structure used for Swift
• Cleaned up test files (organized in separate packages)
• DRYed up the compiler code

Fixes #26

[sav007]

Should we merge this with Operation class ? To be consistent turn Operation class to follow the same pattern as TypeDeclaration and Fragment, extends CodeGenerator and remove this class?

[felipecsl]

Yeah I thought about doing that. Sounds like it could be a good idea for consistency

[sav007]

How about to wrap this to next line for more readability, so it will look like this:

data class Fragment(
    val fragmentName: String,
    val source: String,
    val typeCondition: String,
    val fields: List<Field>,
    val fragmentsSpread: List<String>,
    val inlineFragments: List<String>,
    val fragmentsReferenced: List<String>
) : CodeGenerator {
  /** Returns a Java method that returns the interface represented by this Fragment object. */
  private fun toMethodSpec() =
      MethodSpec.methodBuilder(fragmentName.decapitalize())
          .returns(ClassName.get("", fragmentName.capitalize()))
          .addModifiers(Modifier.PUBLIC, Modifier.ABSTRACT)
          .build()
....

[felipecsl]

Sure!

[sav007]

Awesome this is getting shape

[sav007]

Does this mean that we are regenerating the same fragments all over again if fields reference to the same fragments?

[felipecsl]

Yep, like I said, this is pretty basic and there's a bunch of things to improve. This is one of them 😄

[sav007]

Ok could you pls drop TODO here, that we won't forget it later

[felipecsl]

👍

[sav007]

Shouldn't this go to OperationTypeSpecBuilder so that the name of interface and method will be decided by reference class (OperationTypeSpecBuilder) and not hardcoded here?

[felipecsl]

Sorry, which method are you referring to exactly?

[sav007]

sorry I meant about this genericAccessorMethodSpec. The intention of this is to not make decision about the name of method that returns fragments here but move to the guy who is actually uses it, in our case OperationTypeSpecBuilder

[felipecsl]

Fair enough, will move it

[sav007]

I tried next query:

query SimpleFragment {
	hero {
		...HeroDetailsFragment1
	}
}

fragment HeroDetailsFragment1 on Character {
	name
	friendsConnection {
		totalCount
		edges {
			node {
				name
			}
		}
	}
}

And appears it doesn't generate friendsConnection type.
I guess we can drop a new ticket to support this as this PR will address only simple case