Rewrite Kotest integration in Kotlin.

Author: SimY4

build.sbt

@@ -1,3 +1,5 @@
+import kotlin.Keys._
+
 inThisBuild(
   Seq(
     organization     := "com.github.simy4.coregex",
@@ -170,17 +172,29 @@ lazy val junitQuickcheck = (project in file("junit-quickcheck"))
   .dependsOn(core)
 
 lazy val kotest = (project in file("kotest"))
+  .enablePlugins(KotlinPlugin)
   .settings(
     name        := "kotest",
     moduleName  := "coregex-kotest",
     description := "Kotest bindings for coregex library.",
     libraryDependencies ++= Seq(
-      "io.kotest"            % "kotest-property-jvm" % "6.1.7"                          % Provided,
-      "com.github.sbt.junit" % "jupiter-interface"   % JupiterKeys.jupiterVersion.value % Test
+      "io.kotest"            % "kotest-property-jvm"  % "6.1.7"                          % Provided,
+      "io.kotest"            % "kotest-runner-junit6" % "6.1.7"                          % Test,
+      "com.github.sbt.junit" % "jupiter-interface"    % JupiterKeys.jupiterVersion.value % Test
+    ),
+    crossPaths       := false,
+    autoScalaLibrary := false,
+    kotlinVersion    := "2.2.21",
+    kotlincOptions ++= Seq(
+      "-progressive",
+      "-language-version=2.2",
+      "-api-version=2.2",
+      "-Xexplicit-api=strict",
+      "-Werror"
     ),
+    kotlincJvmTarget := "11",
     testOptions += Tests.Argument(jupiterTestFramework, "-q", "-v")
   )
-  .settings(javaLibSettings(11))
   .settings(jacocoSettings)
   .dependsOn(core)
 

kotest/src/main/java/com/github/simy4/coregex/kotest/CoregexArbitrary.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2021-2026 Alex Simkin
+ *
+ * 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 com.github.simy4.coregex.kotest
+
+import com.github.simy4.coregex.core.Coregex
+import io.kotest.property.Arb
+import io.kotest.property.Classifier
+import io.kotest.property.RTree
+import io.kotest.property.RandomSource
+import io.kotest.property.Sample
+import java.util.regex.Pattern
+import kotlin.streams.toList
+
+public class CoregexArbitrary(private val coregex: Coregex): Arb<String>() {
+
+  public companion object {
+    public fun of(pattern: String, flags: Int = 0): CoregexArbitrary =
+      CoregexArbitrary(Pattern.compile(pattern, flags))
+  }
+
+  public constructor(pattern: Pattern): this(Coregex.from(pattern))
+
+  public constructor(regex: Regex): this(regex.toPattern())
+
+  override val classifier: Classifier<out String> = Classifier { string -> "'$string' matching '$coregex'" }
+
+  override fun edgecase(rs: RandomSource): Sample<String>? = null
+
+  override fun sample(rs: RandomSource): Sample<String> {
+    val seed = rs.random.nextLong()
+    val sample = coregex.generate(seed)
+    return Sample(sample, RTree({ sample }, lazy(CoregexShrinker(coregex, seed))))
+  }
+}
+
+internal class CoregexShrinker(private val coregex: Coregex, private val seed: Long): () -> List<RTree<String>> {
+  override fun invoke(): List<RTree<String>> =
+    coregex
+      .shrink()
+      .map { coregex ->
+        val shrink = coregex.generate(seed)
+        RTree( { shrink }, lazy(CoregexShrinker(coregex, seed)))
+      }
+      .toList()
+}