SBT 0.13 Build.scala References to undefined settings - scala

Question

I am new to SBT and I have been trying to build a custom task for this build.
I have a simple build project:
import sbt._
import Keys._
object JsonBuild extends Build{
lazy val barTask = taskKey[Unit]("some simple task")
val afterTestTask1 = barTask := { println("tests ran!") }
val afterTestTask2 = barTask <<= barTask.dependsOn(test in Test)
lazy val myBarTask = taskKey[Unit]("some simple task")
//val afterMyBarTask1 = myBarTask := { println("tests ran!") }
lazy val afterMyBarTask2 = myBarTask <<= (myBarTask).dependsOn(test in Test) map { _ => println("tests ran!") }
//settings ++ Seq(afterMyBarTask2)
override lazy val settings = super.settings ++ Seq(afterMyBarTask2)
}
I keep getting the error:
References to undefined settings:
{.}/*:myBarTask from {.}/*:myBarTask (C:\Users\haques\Documents\workspace\SBT\jsonParser\project\Build.scala:13)
{.}/test:test from {.}/*:myBarTask (C:\Users\haques\Documents\workspace\SBT\jsonParser\project\Build.scala:13)
Did you mean test:test ?
I have googled around and I cannot find a solution.
Can you explain why it is not working?

Answer 1

lazy val myBarTask = taskKey[Unit]("some simple task")
override lazy val settings = super.settings ++ Seq(myBarTask := { (test in Test).value; println("tests ran!") } )
myBarTask is undefined when you call dependsOn. you should define it before using dependsOn. also value call on key (task/setting) is now preferred way to depend on other keys. you can still use your version, but define myBarTask

Answer 2

This has been bothering.
I did a bit more reading.
I think I know why the above code does not work.
lazy val afterMyBarTask2 = myBarTask <<= (myBarTask).dependsOn(test in Test) map { _ => println("tests ran!") }
When I write (myBarTask).dependsOn(test in Test), the project scope for test is chosen by SBT as ThisBuild.
{.}/test:test from {.}/*:myBarTask (C:\Users\haques\Documents\workspace\SBT\jsonParser\project\Build.scala:13)
ThisBuild project scope does not have the setting test in configuration Test.
Only projects have the setting test.
The key I think that setting is added by some default SBT plugin to the projects settings.
You check what scopes settings exist in SBT by using the inspect command.
If you type in the SBT REPL:
{.}/test:test
The output is:
inspect {.}/test:test
[info] No entry for key.
SBT correctly suggests:
test:test which is:
{file:/C:/Users/haques/Documents/workspace/SBT/jsonParser/}jsonparser/test:test
If the project is not specified in the project scope axis, SBT chooses the current project by default.
Every SBT project if not specified has its own project settings.