Unit test in Play! Framework with Slick

This post comes from my original WordPress blog, written between 2009 and 2018. It is kept here verbatim as an archive — the formatting did not always survive the move, and I no longer agree with all of it.

Testing

The play framework includes some pretty good integration/documentation on how to perform testing however most of it relies on requiring a Play! application to be created (i.e. FakeApplication) and the fact that they share the same database. The second point was the more troublesome one, since in ScalaTest the tests are run in parallel. The following is what I have done to get around these problems.

trait DatabaseInitializationPerTest extends PlaySpec with BeforeAndAfter {
//create a unique database name, which is the class that implements this trat
val dbName = this.toString.toLowerCase()

//the postgres database is always available. Connect to it and drop the current 
//test database (i.e. classname)
// Drop and create the database
val postgres = Database.forURL(s"jdbc:postgresql://localhost/postgres", driver = "org.postgresql.Driver")
  postgres withSession {
    implicit dbServerSession =>
      {
        logger.debug(s"Creating database: $dbName")
        Q.updateNA(s"DROP DATABASE IF EXISTS $dbName; CREATE DATABASE $dbName;").execute
      }
  }

// Connect to the database
implicit lazy val database = Database.forURL(s"jdbc:postgresql://localhost/$dbName", driver = "org.postgresql.Driver");

  before {
    database withSession { implicit session =>
      logger.debug(s"Creating the database: $dbName")
      val evolution_seq = play.api.db.evolutions.Evolutions.applicationEvolutions(new java.io.File("."), this.getClass().getClassLoader(), "default")
      evolution_seq.flatMap(e => EvolutionSqlScript(e.sql_up).statements).foreach{ sql =>
        Q.updateNA(sql).execute
      }
    }
  }

  after {
    database withSession { implicit session =>
      logger.debug(s"Destroying the database: $dbName")
      val evolution_seq = play.api.db.evolutions.Evolutions.applicationEvolutions(new java.io.File("."), this.getClass().getClassLoader(), "default")
      //I believe you have to apply sql_down in the reverse order
      evolution_seq.reverse.flatMap(e => EvolutionSqlScript(e.sql_down).statements).foreach{ sql =>
        Q.updateNA(sql).execute
      }
    }
  }

  /*
   * The following class was taken from the Play framework however they listed theirs as private.
   * @href https://github.com/playframework/playframework/blob/master/framework/src/play-jdbc/src/main/scala/play/api/db/evolutions/Evolutions.scala
   */
  case class EvolutionSqlScript(sql: String) {
    def statements: Seq[String] = {
      // Regex matches on semicolons that neither precede nor follow other semicolons
      sql.split("(?&lt;!;);(?!;)").map(_.trim.replace(";;", ";")).filter(_ != "")
    }
  }

}

The above code makes re-use of the Evolution plugin provided by Play! The code creates Evolution objects (which contain UpSQL and DownSQL statements) and we can apply them on a before / after method before each test.

4 archived comments

applicius 2014-07-14

Acolyte framework can be used to mock up JDBC connection so that Slick (or any other persistence code based on JDBC) can be provided test fixtures, with isolation and simplicity that fit unig testing. http://acolyte.eu.org/

alex 2014-07-25

Hey,

Great work with the plugins, been using your bits for a few years now! Any news on the hypem scraper site coming back online?

Also, your plugin for hypem seems to have lost the ability to add the names of the songs, we just get a gibberish song title now. Can you look into this for us?

Thanks,

Also,

Could you potentially create a ‘Download top 50’ button that essentially clicks all the download buttons for the first 50 tracks?

I’m sure a lot of people like myself use your plugin on the time machine section of the website, and so it would be a great addition to be able to download everything in one go!

Farid Zakaria 2014-08-05

Hey, there has been a change to Chrome where they dis-allow setting the filename for downloading files in the manner at which I am doing them. I am looking for alternatives but in the mean time I dont think I have a great answer :(