Register unitTest generated sources with android studio

[zpencer]

It turns out, android studio does not use the idea plugin and
instead does its own thing.

The android project's non local unit test protos are automatically
registered when we call registerJavaGeneratingTask. But local unit
tests run without the android SDK, and registerJavaGeneratingTask is
not implemented. They must be registered explicitly.

Also, an Android sub project can depend on another subproject that has
GenerateProtoTasks. We must scan through each variant and find such
subproject dependencies, and register their gen outputs.

Android Studio automatically ignores linter warnings for
registerJavaGeneratingTask sources, but for these sources it will
warn. Unfortunately the current version of proto lite generates code
that fails lint, and this causes warnings. But I think the typical
user would rather see warnings than have sources not be registered at
all, so turning this on by default makes sense.

To disable this behavior, set the project property:
protobuf.androidstudio.extrasrcs.experimental=false

fixes #229

[zpencer]

Before:

After:

The unfortunate warnings:

[zpencer]

Just realized that variantData is returning an internal class. Let's see if there's an alternative way to achieve this.

[zhangkun83]

/cc @rschiu from Android SDK team for any comments / suggestions.

[zhangkun83]

Aren't these issues already fixed?
Besides, lint warnings don't seem to be a strong enough case to justify a new flag.

[zpencer]

The latest javalite artifact is still from 2016, so there's no release with the fix yet:
http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22protoc-gen-javalite%22

[zpencer]

@rschiu I wanted to do something like this, but variantData is internal API:

// An android project can depend on a different subproject and use its protos.
// This is not a very common project structure but it is possible.
(getNonTestVariants() + project.android.testVariants
    + project.android.unitTestVariants).each { variant ->
  variant.variantData.variantDependency.compileConfiguration.allDependencies.findAll {
    it instanceof ProjectDependency
  } each {
    ProjectDependency it ->
      it.dependencyProject.tasks.withType(GenerateProtoTask).each {
        GenerateProtoTask generateProtoTask ->
          generateProtoTask.getOutputSourceDirectorySet().srcDirs.each { File outputDir ->
            variant.addJavaSourceFoldersToModel(outputDir)
          }
      }
  }
}

[rschiu]

AFAIK, there is no external API to do that. There is a project to create better API for plugin writers, but I am not on the team anymore and I do not know the current status of that project. I have forwarded this thread to the team internally for their comment.

[zpencer]

@zhangkun83 let's just shoot for this partial fix for now. I think I have found an API to figure this out across sub projects but that API is @Incubating.

[zhangkun83]

LGTM