Play Framework and Slick: testing database-related services - scala

Question

I'm trying to follow the most idiomatic way to having a few fully tested DAO services.
I've got a few case classes such as the following:
case class Person (
id :Int,
firstName :String,
lastName :String
)
case class Car (
id :Int,
brand :String,
model :String
)
Then I've got a simple DAO class like this:
class ADao #Inject()(protected val dbConfigProvider: DatabaseConfigProvider) extends HasDatabaseConfigProvider[JdbcProfile] {
import driver.api._
private val persons = TableQuery[PersonTable]
private val cars = TableQuery[CarTable]
private val personCar = TableQuery[PersonCar]
class PersonTable(tag: Tag) extends Table[Person](tag, "person") {
def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
def firstName = column[String]("name")
def lastName = column[String]("description")
def * = (id, firstName, lastName) <> (Person.tupled, Person.unapply)
}
class CarTable(tag: Tag) extends Table[Car](tag, "car") {
def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
def brand = column[String]("brand")
def model = column[String]("model")
def * = (id, brand, model) <> (Car.tupled, Car.unapply)
}
// relationship
class PersonCar(tag: Tag) extends Table[(Int, Int)](tag, "person_car") {
def carId = column[Int]("c_id")
def personId = column[Int]("p_id")
def * = (carId, personId)
}
// simple function that I want to test
def getAll(): Future[Seq[((Person, (Int, Int)), Car)]] = db.run(
persons
.join(personCar).on(_.id === _.personId)
.join(cars).on(_._2.carId === _.id)
.result
)
}
And my application.conf looks like:
slick.dbs.default.driver="slick.driver.PostgresDriver$"
slick.dbs.default.db.driver="org.postgresql.Driver"
slick.dbs.default.db.url="jdbc:postgresql://super-secrete-prod-host/my-awesome-db"
slick.dbs.default.db.user="myself"
slick.dbs.default.db.password="yolo"
Now by going through Testing with databases and trying to mimic play-slick sample project
I'm getting into so much trouble and I cannot seem to understand how to make my test use a different database (I suppose I need to add a different db on my conf file, say slick.dbs.test) but then I couldn't find out how to inject that inside the test.
Also, on the sample repo, there's some "magic" like Application.instanceCache[CatDAO] or app2dao(app).
Can anybody point me at some full fledged example of or repo that deals correctly with testing play and slick?
Thanks.

Answer 1

I agree it's confusing. I don't know if this is the best solution, but I ended up having a separate configuration file test.conf that specifies an in-memory database:
slick.dbs {
default {
driver = "slick.driver.H2Driver$"
db.driver = "org.h2.Driver"
db.url = "jdbc:h2:mem:play-test"
}
}
and then told sbt to use this when running the tests:
[..] javaOptions in Test ++= Seq("-Dconfig.file=conf/test.conf")