SBT: input task to generate a test source by name - scala

Question

I want to create an sbt task to generate a test source e.g. sbt genSpec Foo should generate FooSpec.scala in src_managed/test
I tried this:
val genSpec = inputKey[File]("Generate spec file")
genSpec := {
import sbt.complete.DefaultParsers._
val log = streams.value.log
val arg: String = spaceDelimited("<arg>").parsed.head //TODO: Single string parser!
val fileName = s"${arg}Spec"
log.info(s"Generating $fileName")
val file = (sourceManaged in Test).value / s"$fileName.scala"
IO.write(file, s"""class $fileName extends AbstractSpec""")
//sourceGenerators in Test += file
file
}
But, even though it is created in the sourceManaged directory, sbt test does not pick it up.
But, this works:
sourceGenerators in Test += Def.task {
val file = (sourceManaged in Test).value / "FooSpec.scala"
IO.write(file, s"""class FooSpec extends AbstractSpec""")
Seq(file)
}.taskValue
But, the above is not exactly what I want - I want to specify Foo as an argument.
So, is there any way to pass arguments to a sourceGenerator task? Or create a task that add something to managed sources such that it is picked up by sbt test?
Also, what is a way to iterate over all compiled sources's filenames? If I can do that, I will simply generate all the Spec.scala from the source filenames itself...
As suggested by this question, I tried this:
val genSpec = taskKey[Seq[File]]("Generate spec file")
genSpec := {
import sbt.complete.DefaultParsers._
val log = streams.value.log
val args = spaceDelimited("<arg>").parsed
args map {arg =>
val fileName = s"${arg}Suite"
log.info(s"Generating $fileName")
val file = (sourceManaged in Test).value / s"$fileName.scala"
IO.write(file, s"""class $fileName extends AbstractSuite""")
file
}
}
genSpec <<= (sourceGenerators in Test) { _.join.map(_.flatten.toList) }
But, I got this error:
error: `parsed` can only be used within an input task macro, such as := or Def.inputTask.
val args = spaceDelimited("<arg>").parsed
^

Answer 1

Try this:
val genSpec = inputKey[File]("Generate spec file")
genSpec := {
import sbt.complete.DefaultParsers._
val log = streams.value.log
val arg: String = spaceDelimited("<arg>").parsed.head //TODO: Single string parser!
val className = s"${arg}Spec"
val file = (sourceManaged in Test).value / s"$className.scala"
log info s"Generating $file"
IO.write(file, s"""class $className extends AbstractSpec""")
file
}
managedSources in Test ++= ((sourceManaged in Test).value ** "*Spec.scala").get