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Remove scalacheck fork by implementing buildableOfCollCond #358

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Merged
merged 1 commit into from
Feb 9, 2023
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Remove scalacheck fork by implementing buildableOfCollCond #358

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2 changes: 1 addition & 1 deletion build.sbt
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Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,7 @@ lazy val core = project
"com.typesafe.akka" %% "akka-stream" % akkaVersion % Test,
"org.scalatest" %% "scalatest" % scalaTestVersion % Test,
"org.scalatestplus" %% scalaTestScalaCheckArtifact % scalaTestScalaCheckVersion % Test,
"org.mdedetrich" %% "scalacheck" % scalaCheckVersion % Test,
"org.scalacheck" %% "scalacheck" % scalaCheckVersion % Test,
"com.rallyhealth" %% "scalacheck-ops_1-16" % scalaCheckOpsVersion % Test,
"com.softwaremill.diffx" %% "diffx-scalatest-must" % diffxVersion % Test,
"com.typesafe.akka" %% "akka-stream-testkit" % akkaVersion % Test,
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22 changes: 21 additions & 1 deletion core/src/test/scala/io/aiven/guardian/kafka/Generators.scala
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Expand Up @@ -3,6 +3,7 @@ package io.aiven.guardian.kafka
import io.aiven.guardian.kafka.models.ReducedConsumerRecord
import org.apache.kafka.common.record.TimestampType
import org.scalacheck.Gen
import org.scalacheck.util.Buildable

import scala.collection.mutable.ListBuffer
import scala.concurrent.duration.FiniteDuration
Expand Down Expand Up @@ -113,6 +114,25 @@ object Generators {
Gen.choose[Long](head.timestamp, last.timestamp - 1).map(millis => FiniteDuration(millis, MILLISECONDS))
}

@SuppressWarnings(
Array(
"scalafix:DisableSyntax.while"
)
)
private def buildableOfCollCond[C <: Iterable[T], T](cond: C => Boolean, g: Gen[C])(implicit
evb: Buildable[T, C]
): Gen[C] =
Gen.infiniteLazyList(g).map { ll =>
val it = ll.iterator
val bldr = evb.builder
while (!cond(bldr.result()))
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The only option I see (without introducing the mutable state) is something like this (pseudo code, probably needs some scalafication):

while (true) {
  val result = bldr.result();
  if (cond(result)) {
    return result;
  }
  bldr ++= it.next()
}

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Thanks for recommendation, I wanted to avoid this because it involved having to circumvent Scala's lint warnings but I managed to find a way. Just pushed it now to see if tests pass.

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So I tried a solution, i.e.

@SuppressWarnings(
  Array(
    "scalafix:DisableSyntax.while",
    "scalafix:DisableSyntax.return"
  )
)
@scala.annotation.nowarn("msg=return statement uses an exception")
private def buildableOfCollCond[C <: Iterable[T], T](cond: C => Boolean, g: Gen[C])(implicit
    evb: Buildable[T, C]
): Gen[C] =
  Gen.infiniteLazyList(g).map { ll =>
    val it   = ll.iterator
    val bldr = evb.builder
    while (true) {
      val result = bldr.result()
      if (cond(result)) {
        return result
      }
      bldr ++= it.next()
    }
    return bldr.result()
  }

And it didn't work/terminate. Don't have time to look at this now so I will make an issue to look at it later as an improvement.

bldr ++= it.next()
bldr.result() // sub-optimal: is called twice for the same result, can be improved!
}

private def listOfFillCond[T](finishCondition: List[T] => Boolean, g: => Gen[List[T]]) =
buildableOfCollCond[List[T], T](finishCondition, g)

def kafkaDateGen(min: Int = 2,
max: Int = 100,
padTimestampsMillis: Range = Range.inclusive(1, 10),
Expand All @@ -121,7 +141,7 @@ object Generators {
topic <- kafkaTopic
records <- {
val base = Generators.kafkaReducedConsumerRecordsGen(topic, min, max, padTimestampsMillis)
condition.fold(base)(c => Gen.listOfFillCond(c, base))
condition.fold(base)(c => listOfFillCond(c, base))
}
} yield records

Expand Down