If you add ScalaCheck to an SBT project like this:
libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.13.4" % "test"
it’s only available in the SBT “test” scope. This means that when you start a Scala REPL session inside of SBT with its
console command, the ScalaCheck library won’t be available in that scope.
To use ScalaCheck with the SBT console (REPL), don’t use its
console command — use
test:console instead. A complete example looks like this:
scala> import org.scalacheck.Gen.choose
Note that after you type
test:console your project may be compiled, so that step may take a few moments.
In summary, use SBT’s
console command to start a “normal” Scala REPL inside SBT, and use
test:console to start a REPL that you can run tests inside of. (Note that this same advice also applies to using ScalaTest or specs2.)