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

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"