BoxSpec.scala

/*
 * Copyright 2007-2011 WorldWide Conferencing, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.liftweb
package common

import org.specs2.mutable.Specification
import org.specs2.ScalaCheck
import org.scalacheck.{Arbitrary, Gen}
import Gen._

import Box._


/* commented out because it tests the compilation phase and we want the compiler to "do the right thing"
object TypeBoundsTest extends Specification with ScalaCheck {
  "Type Bounds Spec".title

  "Type bounds" can {
    "do type testing" in {
      def foo[T: ExcludeThisType.exclude[Nothing]#other](a: T) = a.toString
      foo(33.0)
      foo(throw new Exception("foo"))

      true == true
    }
  }
}

*/

/**
 * System under specification for Box.
 */
class BoxSpec extends Specification with ScalaCheck with BoxGenerator {

  "A Box" can {
    "be created from a Option. It is Empty if the option is None" in {
      Box(None) must beEmpty
    }
    "be created from a Option. It is Full(x) if the option is Some(x)" in {
      Box(Some(1)) must_== Full(1)
    }
    "be created from a List containing one element. It is Empty if the list is empty" in {
      Box(Nil) must beEmpty
    }
    "be created from a List containing one element. It is Full(x) if the list is List(x)" in {
      Box(List(1)) must_== Full(1)
    }
    "be created from a List containing more than one element. It is Full(x) if the list is x::rest" in {
      Box(List(1, 2, 3)) must_== Full(1)
    }
    "be used as an iterable" in {
      Full(1) reduceLeft {(x: Int, y: Int) => x + y} must_== 1
    }
    "be used as an Option" in {
      Full(1) orElse Some(2) must_== Some(1)
      Empty orElse Some(2) must_== Some(2)
    }
    "be implicitly defined from an Option. The openOrThrowException method can be used on an Option for example" in {
      Some(1).openOrThrowException("This is a test") must_== 1
    }
    "be defined from some legacy code (possibly passing null values). If the passed value is not null, a Full(value) is returned" in {
      Box.legacyNullTest("s") must_== Full("s")
    }
    "be defined from some legacy code (possibly passing null values). If the passed value is null, an Empty is returned" in {
      Box.legacyNullTest(null) must_== Empty
    }
  }

  "A Box" should {
    "provide a 'choice' method to either apply a function to the Box value or return another default can" in {
      def gotIt = (x: Int) => Full("got it: " + x.toString)

      Full(1).choice(gotIt)(Full("nothing")) must_== Full("got it: 1")
      Empty.choice(gotIt)(Full("nothing")) must_== Full("nothing")
    }
  }

  "A Full Box" should {
    "not beEmpty" in {
      Full(1).isEmpty must beFalse
    }
    "be defined" in {
      Full(1).isDefined must beTrue
    }
    "return its value when opened" in {
      Full(1).openOrThrowException("This is a test") must_== 1
    }
    "return its value when opened with openOr(default value)" in {
      Full(1) openOr 0 must_== 1
    }
    "return itself when or'ed with another Box" in {
      Full(1) or Full(2) must_== Full(1)
    }
    "define an 'exists' method returning true if the Box value satisfies the function" in {
      Full(1) exists {_ > 0} must beTrue
    }
    "define an exists method returning false if the Box value doesn't satisfy the function" in {
      Full(0) exists {_ > 0} must beFalse
    }
    "define a forall method returning true if the Box value satisfies the function" in {
      Full(1) forall {_ > 0} must beTrue
    }
    "define a forall method returning false if the Box value doesn't satisfy the function" in {
      Full(0) forall {_ > 0} must beFalse
    }
    "define a 'filter' method, returning a Full Box if the filter is satisfied" in {
      Full(1) filter {_ > 0} must_== Full(1)
    }
    "define a 'filter' method, returning Empty if the filter is not satisfied" in {
      Full(1) filter {_ == 0} must beEmpty
    }
    "define a 'filterMsg' method, returning a Failure if the filter predicate is not satisfied" in {
      Full(1).filterMsg("not equal to 0")(_ == 0) must_== Failure("not equal to 0", Empty, Empty)
    }
    "define a 'foreach' method using its value (to display it for instance)" in {
      var total = 0
      Full(1) foreach { total += _ }
      total must_== 1
    }
    "define a 'map' method to transform its value" in {
      Full(1) map { _.toString } must_== Full("1")
    }
    "define a 'flatMap' method transforming its value in another Box. If the value is transformed in a Full can, the total result is a Full can" in {
      Full(1) flatMap { x: Int => if (x > 0) Full("full") else Empty } must_== Full("full")
    }
    "define a 'flatMap' method transforming its value in another Box. If the value is transformed in an Empty can, the total result is an Empty can" in {
      Full(0) flatMap { x: Int => if (x > 0) Full("full") else Empty } must beEmpty
    }
    "define an 'elements' method returning an iterator containing its value" in {
      Full(1).elements.next must_== 1
    }
    "define a 'toList' method returning a List containing its value" in {
      Full(1).toList must_== List(1)
    }
    "define a 'toOption' method returning a Some object containing its value" in {
      Full(1).toOption must_== Some(1)
    }
    "return itself if asked for its status with the operator ?~" in {
      Full(1) ?~ "error" must_== Full(1)
    }
    "return itself if asked for its status with the operator ?~!" in {
      Full(1) ?~! "error" must_== Full(1)
    }
    "define a 'pass' method passing the can to a function and returning itself (alias: $)" in {
      var empty = false
      def emptyString(s: Box[String]) = s foreach {c: String => empty = c.isEmpty}
      Full("") $ emptyString _
      empty must beTrue
    }
    "define a 'run' method either returning a default value or applying a user-defined function on it" in {
      def appendToString(s: String, x: Int) = s + x.toString
      Full(1).run("string")(appendToString) must_== "string1"
    }
    "define a 'isA' method returning a Full(value) if the value is the instance of a given class" in {
      Full("s").isA(classOf[String]) must_== Full("s")
    }
    "define a 'isA' method returning Empty if the value is not the instance of a given class" in {
      Full("s").isA(classOf[Double]) must_== Empty
    }
    "define a 'asA' method returning a Full(value) if the value is the instance of a given type" in {
      Full("s").asA[String] must_== Full("s")
    }
    "define a 'asA' method returning Empty if the value is not the instance of a given type" in {
      Full("s").asA[Double] must_== Empty
    }

    "define a 'asA' method must work with Boolean" in {
      Full(true).asA[Boolean] must_== Full(true)
      Full(3).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Character" in {
      Full('a').asA[Char] must_== Full('a')
      Full('a').asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Byte" in {
      Full(3.toByte).asA[Byte] must_== Full(3.toByte)
      Full(3.toByte).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Double" in {
      Full(44d).asA[Double] must_== Full(44D)
      Full(44d).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Float" in {
      Full(32f).asA[Float] must_== Full(32f)
      Full(33f).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Integer" in {
      Full(3).asA[Int] must_== Full(3)
      Full(3).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Long" in {
      Full(32L).asA[Long] must_== Full(32L)
      Full(32L).asA[Boolean] must_== Empty
    }

    "define a 'asA' method must work with Short" in {
      Full(8.toShort).asA[Short] must_== Full(8.toShort)
      Full(8.toShort).asA[Boolean] must_== Empty
    }

  }

  "An Empty Box" should {
    "beEmpty" in {
      Empty.isEmpty must beTrue
    }
    "not be defined" in {
      Empty.isDefined must beFalse
    }
    "throw an exception if opened" in {
      {Empty.openOrThrowException("See what happens?, at least we expect it in this case :)"); ()} must throwA[NullPointerException]
    }
    "return a default value if opened with openOr" in {
      Empty.openOr(1) must_== 1
    }
    "return the other Box if or'ed with another Box" in {
      Empty.or(Full(1)) must_== Full(1)
    }
    "return itself if filtered with a predicate" in {
      val empty: Box[Int] = Empty
      empty.filter {_ > 0} must beEmpty
    }
    "define an 'exists' method returning false" in {
      val empty: Box[Int] = Empty
      empty exists {_ > 0} must beFalse
    }
    "define a 'forall' method returning true" in {
      val empty: Box[Int] = Empty
      empty forall {_ > 0} must beTrue
    }
    "define a 'filter' method, returning Empty" in {
      val empty: Box[Int] = Empty
      empty filter {_ > 0} must beEmpty
    }
    "define a 'filterMsg' method, returning a Failure" in {
      Empty.filterMsg("not equal to 0")(_ == 0) must_== Failure("not equal to 0", Empty, Empty)
    }
    "define a 'foreach' doing nothing" in {
      var total = 0
      val empty: Box[Int] = Empty
      empty foreach {total += _}
      total must_== 0
    }
    "define a 'map' method returning Empty" in {
      Empty map {_.toString} must beEmpty
    }
    "define a 'flatMap' method returning Empty" in {
      Empty flatMap {x: Int => Full("full")} must beEmpty
    }
    "define an 'elements' method returning an empty iterator" in {
      Empty.elements.hasNext must beFalse
    }
    "define a 'toList' method returning Nil" in {
      Empty.toList must_== Nil
    }
    "define a 'toOption' method returning None" in {
      Empty.toOption must_== None
    }
    "return a failure with a message if asked for its status with the operator ?~" in {
      Empty ?~ "nothing" must_== Failure("nothing", Empty, Empty)
    }
    "return a failure with a message if asked for its status with the operator ?~!" in {
      Empty ?~! "nothing" must_== Failure("nothing", Empty, Empty)
    }
    "define a 'isA' method returning Empty" in {
      Empty.isA(classOf[Double]) must_== Empty
    }
    "define a 'asA' method returning Empty" in {
      Empty.asA[Double] must_== Empty
    }
  }

  "A Failure is an Empty Box which" can {
    "return its cause as an exception" in {
      case class LiftException(m: String) extends Exception
      Failure("error", Full(new LiftException("broken")), Empty).exception must_== Full(new LiftException("broken"))
    }
    "return a chained list of causes" in {
      Failure("error",
              Full(new Exception("broken")),
              Full(Failure("nested cause", Empty, Empty))).chain must_== Full(Failure("nested cause", Empty, Empty))
    }
    "be converted to a ParamFailure" in {
      Failure("hi mom") ~> 404 must_== ParamFailure("hi mom", Empty, Empty, 404)
    }
  }

  "A Failure is an Empty Box which" should {
    "return itself if mapped or flatmapped" in {
      Failure("error", Empty, Empty) map {_.toString} must_== Failure("error", Empty, Empty)
      Failure("error", Empty, Empty) flatMap {x: String => Full(x.toString)} must_== Failure("error", Empty, Empty)
    }
    "return a itself when asked for its status with the operator ?~" in {
      Failure("error", Empty, Empty) ?~ "nothing" must_== Failure("error", Empty, Empty)
    }
    "create a new failure with a chained message if asked for its status with the operator ?~!" in {
      Failure("error", Empty, Empty) ?~! "error2" must_== Failure("error2", Empty, Full(Failure("error", Empty, Empty)))
    }
    "return false for exist method" in {
      Failure("error", Empty, Empty) exists {_ => true } must beFalse
    }
    "return true for forall method" in {
      Failure("error", Empty, Empty) forall {_ => false } must beTrue
    }
  }

  "A ParamFailure is a failure which" should {
    "appear in the chain when ~> is invoked on it" in {
      Failure("Apple") ~> 404 ~> "apple" must_==
        ParamFailure("Apple", Empty, Full(
          ParamFailure("Apple", Empty, Empty, 404)
        ), "apple")
    }
  }

  "A Box equals method" should {

    "return true with comparing two identical Box messages" in check {
      (c1: Box[Int], c2: Box[Int]) => (c1, c2) match {
        case (Empty, Empty) => c1 must_== c2
        case (Full(x), Full(y)) => (c1 == c2) must_== (x == y)
        case (Failure(m1, e1, l1), Failure(m2, e2, l2)) => (c1 == c2) must_== ((m1, e1, l1) == (m2, e2, l2))
        case _ => c1 must be_!=(c2)
      }
    }

    "return false with comparing one Full and another object" in {
      Full(1) must be_!=("hello")
    }

    "return false with comparing one Empty and another object" in {
      Empty must be_!=("hello")
    }

    "return false with comparing one Failure and another object" in {
      Failure("", Empty, Empty) must be_!=("hello")
    }
  }

  "A List[Box[T]]" should {
    "be convertable to a Box[List[T]] when all are Full" in {
      val someBoxes: List[Box[String]] = List(Full("bacon"), Full("sammich"))
      val singleBox = someBoxes.toSingleBox("Box failed!")

      singleBox must_== Full(List("bacon", "sammich"))
    }

    "be convertable to a Box[List[T]] when some are Full and some are Empty" in {
      val someBoxes: List[Box[String]] = List(Full("bacon"), Full("sammich"), Empty)
      val singleBox = someBoxes.toSingleBox("Box failed!")

      singleBox must_== Full(List("bacon", "sammich"))
    }

    "be convertable to a ParamFailure[Box[List[T]]] when any are Failure" in {
      val someBoxes: List[Box[String]] = List(Full("bacon"), Full("sammich"), Failure("I HATE BACON"))
      val singleBox = someBoxes.toSingleBox("This should be in the param failure.")

      singleBox must beLike {
        case ParamFailure(message, _, _, _) =>
          message must_== "This should be in the param failure."
      }
    }

    "chain the ParamFailure to the failures in the list when any are Failure" in {
      val someBoxes: List[Box[String]] = List(Full("bacon"), Failure("I HATE BACON"), Full("sammich"), Failure("MORE BACON FAIL"), Failure("BACON WHY U BACON"))

      val singleBox = someBoxes.toSingleBox("Failure.")

      val expectedChain =
        Failure("I HATE BACON", Empty,
          Full(Failure("MORE BACON FAIL", Empty,
            Full(Failure("BACON WHY U BACON")))))

      singleBox must beLike {
        case ParamFailure(_, _, chain, _) =>
          chain must_== Full(expectedChain)
      }
    }
  }

}


trait BoxGenerator {

  implicit def genThrowable: Arbitrary[Throwable] = Arbitrary[Throwable] {
    case object UserException extends Throwable
    value(UserException)
  }

  implicit def genBox[T](implicit a: Arbitrary[T]): Arbitrary[Box[T]] = Arbitrary[Box[T]] {
    frequency(
      (3, value(Empty)),
      (3, a.arbitrary.map(Full[T])),
      (1, genFailureBox)
    )
  }

  def genFailureBox: Gen[Failure] = for {
    msgLen <- choose(0, 4)
    msg <- listOfN(msgLen, alphaChar)
    exception <- value(Full(new Exception("")))
    chainLen <- choose(1, 5)
    chain <- frequency((1, listOfN(chainLen, genFailureBox)), (3, value(Nil)))
  } yield Failure(msg.mkString, exception, Box(chain.headOption))

}