A stub-centric test syntax in Scala

AddressMapper.scala

/** System under test */
package net.rafaelferreira

case class Street(streetName: String)
case class City(name:String)
case class Address(city:City, street:Street)

trait AddressMapper {
  def map(id:String): Option[Address]
}

trait Database {
  def find(table:String, id:String): Option[Map[String,String]]
}

class DatabaseBackedAddressMapper(db:Database) extends AddressMapper {
  override def map(id:String): Option[Address] = { 
    for (address <- db.find("addresses", id);
         city <- db.find("cities", address("city"));
         street <- db.find("streets", address("street")))
    yield Address(City(city("name")),Street(street("name")))
  }
}

AddressMapperSpec.scala

package net.rafaelferreira

import org.specs2.Specification

class AddressMapperSpec extends Specification with Goose {
  val id = dep[String]
  val database = dep[Database]

  def is = check(new DatabaseBackedAddressMapper(database()).map(id())) {
    _.when(id ==> "123").
      and(database.stub(_.find("addresses", "123")) ==> Some(Map("city" -> "789", "street" -> "999"))).
      and(database.stub(_.find("cities", "789")) ==> Some(Map("name" -> "Curitiba"))).
      but {
        _.when(database.stub(_.find("streets", "999")) ==>  None).
        then(_ must_== None)
      }.
      but {
        _.when(database.stub(_.find("streets", "999")) ==> Some(Map("name" -> "St. st."))).
        then(_ must_== Some(Address(City("Curitiba"), Street("St. st."))))
      }
  }
}

So far I have this syntax working, but the test reporting is tricky. I'm now looking into how to abuse Specs2' auto-examples feature.

Further work here: https://github.com/rafaeldff/goose