Why does sbt say "bad symbolic reference..." for test with ScalaTest? - scala

Question

I started using ScalaTest with sbt. The build.sbt is as follows:
name := "MySpecSample"
version := "1.0"
libraryDependencies += "org.scalatest" % "scalatest_2.11" % "2.2.0" % "test"
scalaVersion := "2.10.3"
Initial test code is here. This test code runs alone without main component code.
import collection.mutable.Stack
import org.scalatest._
class ExampleSpec extends FlatSpec with Matchers {
"A Stack" should "pop values in last-in-first-out order" in {
val stack = new Stack[Int]
stack.push(1)
stack.push(2)
stack.pop() should be (2)
stack.pop() should be (1)
}
it should "throw NoSuchElementException if an empty stack is popped" in {
val emptyStack = new Stack[Int]
a [NoSuchElementException] should be thrownBy {
emptyStack.pop()
}
}
}
I wrote it according to Official quick start.
But it doesn't work properly. The error message is as follows:
> test
[info] Compiling 1 Scala source to /Users/kaisasak/untitled/target/scala-2.10/test-classes...
[error] bad symbolic reference. A signature in package.class refers to type compileTimeOnly
[error] in package scala.annotation which is not available.
[error] It may be completely missing from the current classpath, or the version on
[error] the classpath might be incompatible with the version used when compiling package.class.
[error] /Users/kaisasak/untitled/src/test/scala/ExampleSpec.scala:6: Reference to class FlatSpec in package scalatest should not have survived past type checking,
[error] it should have been processed and eliminated during expansion of an enclosing macro.
[error] class ExampleSpec extends FlatSpec with Matchers {
[error] ^
[error] two errors found
[error] (test:compile) Compilation failed
[error] Total time: 3 s, completed Jun 29, 2014 11:20:41 AM
I can find same problems on Google but no good answer was available.
My environment is here.
MacOSX 10.9.3
Scala 2.10.3
sbt 0.13.2
I tried with sbt 0.13.1 after downgrading, but the result is the same to the one of 0.13.2. What should I do to use ScalaTest with sbt?

Answer 1

In your build.sbt you set the version of Scala to 2.10.3 with the following:
scalaVersion := "2.10.3"
However the ScalaTest dependency uses Scala 2.11 explicitly (note the _2.11 part):
"org.scalatest" % "scalatest_2.11" % "2.2.0" % "test"
You have to use the same major scala version for both.
With sbt you can simply ensure this using %% instead of % as follows:
"org.scalatest" %% "scalatest" % "2.2.0" % "test"