Paul Butcher

For an updated version of this post that covers Scala 2.9.1 and sbt 0.10, go here.

I spent quite a bit of time beating my head against the details of getting Scala 2.8.0.RC1, sbt and ScalaTest to play nicely with each other. So here’s a step-by-step guide which will hopefully save others time.

1. Install sbt
2. Create a new project as follows:

   $ mkdir aproject
   $ cd aproject/
   $ sbt
   Project does not exist, create new project? (y/N/s) y
   Name: aproject
   Organization: com.example
   Version [1.0]:
   Scala version [2.7.7]: 2.8.0.RC1
   sbt version [0.7.3]:
   

3. Create a build configuration file in project/build/AProject.scala containing:

   import sbt._
   
   class AProject(info: ProjectInfo) extends DefaultProject(info) {
     val scalaToolsSnapshots = ScalaToolsSnapshots
     val scalatest = "org.scalatest" % "scalatest" %
       "1.0.1-for-scala-2.8.0.RC1-SNAPSHOT"
   }
   

   This tells sbt that you will be using the pre-release snapshot version of ScalaTest for Scala 2.8.0.RC1.

4. Download the ScalaTest library with sbt update. After running this, you should see that you have a lib_managed directory containing the ScalaTest jar.
5. Create src/main/scala/Widget.scala containing:

   package com.example
   
   class Widget {
     def colour = "Blue"
     def disposition = "Awesome"
   }

6. Create src/test/scala/WidgetSpec.scala containing:

   package com.example.test
   
   import org.scalatest.Spec
   import com.example.Widget
   
   class WidgetSpec extends Spec {
   
     describe("A Widget") {
   
       it("should be blue") {
         expect("Blue") { new Widget().colour }
       }
   
       it("should be awesome") {
         expect("Awesome") { new Widget().disposition }
       }
     }
   }
   

7. Run your tests with sbt test. You should see:

   [info] == com.example.test.WidgetSpec ==
   [info] A Widget
   [info] Test Starting: A Widget should be blue
   [info] Test Passed: A Widget should be blue
   [info] Test Starting: A Widget should be awesome
   [info] Test Passed: A Widget should be awesome
   [info] == com.example.test.WidgetSpec ==
   

8. Create src/main/scala/Main.scala containing:

   package com.example
   
   object Main {
     def main(args: Array[String]) {
       val w = new Widget()
       println("My new widget is "+ w.colour)
     }
   }
   

9. Run your program with sbt run. You should see:

   [info] Running com.example.Main
   My new widget is Blue
   

Update: Use the pre-defined ScalaToolsSnapshots repo (thanks to Erick Fleming).

Update: Fixed a typo in step 8 (thanks to Jason).