Invoking a subproject's main with a custom task

Question

I have a project performing integration tests for a bunch of projects which are all bundled in the same multi-project build with it. The integration tests run through a regular main (object Runner extends App).

I wish being able to run it from the root project of the multi-project build through a task or command named integrationTest, so I try:

val integrationTest = taskKey[Unit]("Executes integration tests.")

lazy val root = (project in file(".")).aggregate(projIntegrationTest, projA, projB, ...).settings(
  integrationTest := (run in Compile in projIntegrationTest).value
)

Which does nothing when I issue integrationTest on the prompt, only emitting:

[success] Total time: 0 s, completed Oct 23, 2015 12:31:21 AM

How may I approach finding out why does it not get run when my custom task integrationTest runs?

Oddly, replacing run with compile or publishlocal in integrationTest := (run in Compile in projIntegrationTest).value above, my custom task line acts as expected and takes care of compiling or publishing when the custom task is executed.

Answer 1

It doesn't work because run is an InputTask, not a regular Task.

You need to do:

integrationTest :=
  (run in Compile in projIntegrationTest)
    .toTask("").value

this is covered in the "Get a Task from an InputTask" section of http://www.scala-sbt.org/0.13/docs/Input-Tasks.html.

As of sbt 0.13.13 your code gives:

warning: `value` is deprecated for an input task. Use `evaluated` or `inputTaskValue`.

This is a nice improvement; earlier versions of sbt let this pass, making it hard to troubleshoot. (But note that the deprecation message suggests a different solution than I've used here; I haven't investigated that discrepancy. Can someone shed some light on that?)