build-2.sbt

name := "hello"

version := "1.0"

scalaVersion := "2.11.0"

libraryDependencies += "org.scalatest" %% "scalatest" % "2.1.5" % "test"

build.sbt

name := "hello"

version := "1.0"

scalaVersion := "2.11.0"

Hello-2.scala

class HelloSbt {
  def sayHello() = ""
}

Hello-3.scala

class HelloSbt {
  def sayHello(name: String) = s"Hello, $name!"
}

Hello.scala

object Hello {
  def main(args: Array[String]) = println("Hello, SBT!")
}