Cannot auto-extract case class

[byF]

Environment:

• Scala 2.10.5
• Rapture both 2.0.0-M5 and 2.0.0-M6
• Spray JSON 1.3.2

package com.test

import org.scalatest.{FlatSpec, ShouldMatchers}
import rapture.json._
import rapture.json.jsonBackends.spray._

class RaptureTest extends FlatSpec with ShouldMatchers {

  case class CC(s: String, t: String)

  "Case class" should "be extracted from JSON" in {
    val json = json"""{"s":"abc","t":"def"}"""
    val cc = json.as[CC]
    cc should be CC("abc","def")
  }

}

This fails with

Error:(13, 21) cannot extract type RaptureTest.this.CC from rapture.json.Json.
    val cc = json.as[CC]

We've spent the whole afternoon on this, not sure where the problem lays.

[propensive]

It's interesting that when copy/pasting this into the REPL I get:

<console>:25: error: value CC is not a member of RaptureTest.this.ResultOfBeWordForAny[RaptureTest.this.CC]
    cc should be CC("abc","def")
                 ^

[propensive]

Note that the following works fine:

scala> import rapture.json._
import rapture.json._

scala> import rapture.json.jsonBackends.spray._
import rapture.json.jsonBackends.spray._

scala> case class CC(s: String, t: String)
defined class CC

scala> val json = json"""{"s":"abc","t":"def"}"""
json: rapture.json.Json = json"""{"s":"abc","t":"def"}"""

scala> val cc = json.as[CC]
cc: CC = CC(abc,def)

[propensive]

I've noticed that if I change the test to this, it compiles:

package com.test

import org.scalatest.{FlatSpec, ShouldMatchers}
import rapture.json._
import rapture.json.jsonBackends.spray._

class RaptureTest extends FlatSpec with ShouldMatchers {
  case class CC(s: String, t: String)
  "Case class" should "be extracted from JSON" in {
    val json = json"""{"s":"abc","t":"def"}"""
    val cc = json.as[CC]
    cc shouldBe CC("abc", "def")
  }
}

My best guess is that there's a macro in ScalaTest (I'm not overly familiar with it), and it's getting confused in some way.

Does that help you at all?

[byF]

Actually, I extracted the issue into a case so I could share with you. This is happening in our codebase, basically the same thing with some actual business logic around.

I worked around it defining a custom CC JSON extractor, however I'll investigate further this week.

[propensive]

Thanks for spending the time on it. I seem to remember I saw something similar a while ago (and was able to fix it in the same way), though I was never able to reduce it to such a small test case. As with your example, it worked fine copy/pasting into the REPL...

Let me know if you'd like me to schedule some time to investigate it further. If it's the same issue I was having, I'd really like to get to the bottom of it...