Question

I am trying to learn the unit tests in Play scala, but I am running into some issues. I am trying to run several tests on my models layer like this:

"User Model" should {
    "be created and retrieved by username" in {
        running(FakeApplication()) {
            val newUser = User(username = "weezybizzle",password = "password")
            User.save(newUser)
            User.findOneByUsername("weezybizzle") must beSome
        }
    }
    "another test" in {
        running(FakeApplication()) {
            // more tests involving adding and removing users
        }
    }
}

However when doing things this way, I fail to connect to the database on the second unit test, saying that the connection is closed. I tried to solve this by enclosing all the code in a block that runs on the same fake application, but that didn’t work either.

  running(FakeApplication()) {
    "be created and retrieved by username" in {
        val newUser = User(username = "weezybizzle",password = "password")
        User.save(newUser)
        User.findOneByUsername("weezybizzle") must beSome
    }
    "another test" in {
        // more tests involving adding and removing users
    }
  }

Answer 1

The specs2 tests are performed by default in parallel which may cause problems with accessing databases, especially when you rely on the db contents provided by a previous test. So to force sequential testing you have to tell specs2 to do so:

class ModelSpec extends Specification with Logging {
  override def is = args(sequential = true) ^ super.is
...
}

For tests done in one FakeApplication you can wrap the whole tests in it:

  running(FakeApp) {
    log.trace("Project tests.")
    val Some(project) = Project.findByName("test1")

    "Project" should {

      "be retrieved by name" in {
        project must beAnInstanceOf[Project]
        project.description must endWith("project")
      }

The whole sample can be found here. That was my first attempt to deal with problems while testing MongoDB with Play! framework.

The second approach I borrowed from the salat project, which is by the way a very good source of specs examples dealing with MongoDB (although it is not a Play! framework app). You have to define a trait extending Around and Scope, where you can put anything you need to be initialized in an application instance:

import org.specs2.mutable._
import org.specs2.execute.StandardResults

import play.api.mvc._
import play.api.mvc.Results
import play.api.test._
import play.api.test.Helpers._

trait FakeApp extends Around with org.specs2.specification.Scope {

  val appCfg = Map(
    "first.config.key" -> "a_value",
    "second.config.key" -> "another value"
  )

  object FakeApp extends FakeApplication(
      additionalPlugins = Seq("com.github.rajish.deadrope.DeadropePlugin"),
      additionalConfiguration = appCfg
    ) {
    // override val routes = Some(Routes)
  }

  def around[T <% org.specs2.execute.Result](test: => T) = running(FakeApp) {
    Logger.debug("Running test ==================================")
    test  // run tests inside a fake application
  }
}

Edit 2013-06-30:

In the current version of specs2 the around signature should be:

def around[T : AsResult](test: => T): Result

End of edit

Then a test can be written like that:

class SomeSpec extends Specification { sequential // according to @Eric comment

  "A test group" should {
    "pass some tests" in new FakeApp {
      1 must_== 1
    }

    "and these sub-tests too" in {
      "first subtest" in new FakeApp {
         success
      }
      "second subtest" in new FakeApp {
         failure
      }
    }
  }
}

A full sample of such suite can be found here.

On a final note: It’s also good to clean up the test database before starting a suite:

  step {
    MongoConnection().dropDatabase("test_db")
  }