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How to use edgecase method of io.kotest.property.arbitrary.map class

Best Kotest code snippet using io.kotest.property.arbitrary.map.edgecase

builders.kt

Source:builders.kt

...44/**45 * Creates a new [Arb] that performs no shrinking, uses the given edge cases and46 * generates values from the given function.47 */48fun <A> arbitrary(edgecases: List<A>, fn: suspend ArbitraryBuilderContext.(RandomSource) -> A): Arb<A> =49   object : Arb<A>() {50      override fun edgecase(rs: RandomSource): A? = if (edgecases.isEmpty()) null else edgecases.random(rs.random)51      override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)52      private val delegate = arbitraryBuilder { rs -> fn(rs) }53   }54/**55 * Creates a new [Arb] that performs shrinking using the supplied [Shrinker], uses the given edge cases and56 * generates values from the given function.57 */58fun <A> arbitrary(59   edgecases: List<A>,60   shrinker: Shrinker<A>,61   fn: suspend ArbitraryBuilderContext.(RandomSource) -> A62): Arb<A> = object : Arb<A>() {63   override fun edgecase(rs: RandomSource): A? = if (edgecases.isEmpty()) null else edgecases.random(rs.random)64   override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)65   private val delegate = arbitraryBuilder(shrinker) { rs -> fn(rs) }66}67/**68 * Creates a new [Arb] that generates edge cases from the given [edgecaseFn] function69 * and generates samples from the given [sampleFn] function.70 */71fun <A> arbitrary(72   edgecaseFn: (RandomSource) -> A?,73   sampleFn: suspend ArbitraryBuilderContext.(RandomSource) -> A74): Arb<A> =75   object : Arb<A>() {76      override fun edgecase(rs: RandomSource): A? = edgecaseFn(rs)77      override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)78      private val delegate: Arb<A> = arbitraryBuilder { rs -> sampleFn(rs) }79   }80/**81 * Creates a new [Arb] that generates edge cases from the given [edgecaseFn] function,82 * performs shrinking using the supplied [Shrinker], and generates samples from the given [sampleFn] function.83 */84fun <A> arbitrary(85   edgecaseFn: (RandomSource) -> A?,86   shrinker: Shrinker<A>,87   sampleFn: suspend ArbitraryBuilderContext.(RandomSource) -> A88): Arb<A> =89   object : Arb<A>() {90      override fun edgecase(rs: RandomSource): A? = edgecaseFn(rs)91      override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)92      private val delegate: Arb<A> = arbitraryBuilder(shrinker) { rs -> sampleFn(rs) }93   }94/**95 * Creates a new [Arb] that performs no shrinking, has no edge cases and96 * generates values from the given function.97 */98suspend inline fun <A> generateArbitrary(99   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A100): Arb<A> = suspendArbitraryBuilder { rs -> fn(rs) }101/**102 * Creates a new [Arb] that performs shrinking using the supplied [Shrinker], has no edge cases and103 * generates values from the given function.104 */105suspend inline fun <A> generateArbitrary(106   shrinker: Shrinker<A>,107   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A108): Arb<A> = suspendArbitraryBuilder(shrinker, null) { rs -> fn(rs) }109/**110 * Creates a new [Arb] that classifies the generated values using the supplied [Classifier], has no edge cases and111 * generates values from the given function.112 */113suspend inline fun <A> generateArbitrary(114   classifier: Classifier<A>,115   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A116): Arb<A> = suspendArbitraryBuilder(null, classifier) { rs -> fn(rs) }117/**118 * Creates a new [Arb] that performs shrinking using the supplied [Shrinker],119 * classifies the generated values using the supplied [Classifier], has no edge cases and120 * generates values from the given function.121 */122suspend inline fun <A> generateArbitrary(123   shrinker: Shrinker<A>,124   classifier: Classifier<A>,125   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A126): Arb<A> = suspendArbitraryBuilder(shrinker, classifier) { rs -> fn(rs) }127/**128 * Creates a new [Arb] that performs no shrinking, uses the given edge cases and129 * generates values from the given function.130 */131suspend inline fun <A> generateArbitrary(132   edgecases: List<A>,133   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A134): Arb<A> = suspendArbitraryBuilder(null, null,135   if (edgecases.isEmpty()) null else { rs -> edgecases.random(rs.random) }136) { rs -> fn(rs) }137/**138 * Creates a new [Arb] that performs shrinking using the supplied [Shrinker], uses the given edge cases and139 * generates values from the given function.140 */141suspend inline fun <A> generateArbitrary(142   edgecases: List<A>,143   shrinker: Shrinker<A>,144   crossinline fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A145): Arb<A> = suspendArbitraryBuilder(146   shrinker,147   null,148   if (edgecases.isEmpty()) null else { rs -> edgecases.random(rs.random) }149) { rs -> fn(rs) }150/**151 * Creates a new [Arb] that generates edge cases from the given [edgecaseFn] function152 * and generates samples from the given [sampleFn] function.153 */154suspend inline fun <A> generateArbitrary(155   crossinline edgecaseFn: (RandomSource) -> A?,156   crossinline sampleFn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A157): Arb<A> {158   val delegate: Arb<A> = suspendArbitraryBuilder { rs -> sampleFn(rs) }159   return object : Arb<A>() {160      override fun edgecase(rs: RandomSource): A? = edgecaseFn(rs)161      override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)162   }163}164/**165 * Creates a new [Arb] that generates edge cases from the given [edgecaseFn] function,166 * performs shrinking using the supplied [Shrinker], and generates samples from the given [sampleFn] function.167 */168suspend inline fun <A> generateArbitrary(169   crossinline edgecaseFn: (RandomSource) -> A?,170   shrinker: Shrinker<A>,171   crossinline sampleFn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A172): Arb<A> {173   val delegate: Arb<A> = suspendArbitraryBuilder(shrinker) { rs -> sampleFn(rs) }174   return object : Arb<A>() {175      override fun edgecase(rs: RandomSource): A? = edgecaseFn(rs)176      override fun sample(rs: RandomSource): Sample<A> = delegate.sample(rs)177   }178}179/**180 * Creates a new [Arb] using [Continuation] using a stateless [builderFn].181 *182 * This function accepts an optional [shrinker], [classifier], and [edgecaseFn]. These parameters183 * will be passed to [ArbitraryBuilder].184 */185fun <A> arbitraryBuilder(186   shrinker: Shrinker<A>? = null,187   classifier: Classifier<A>? = null,188   edgecaseFn: EdgecaseFn<A>? = null,189   builderFn: suspend ArbitraryBuilderContext.(RandomSource) -> A190): Arb<A> = object : Arb<A>() {191   override fun edgecase(rs: RandomSource): A? = singleShotArb(SingleShotGenerationMode.Edgecase, rs).edgecase(rs)192   override fun sample(rs: RandomSource): Sample<A> = singleShotArb(SingleShotGenerationMode.Sample, rs).sample(rs)193   override val classifier: Classifier<out A>? = classifier194   /**195    * This function generates a new instance of a single shot arb.196    * DO NOT CACHE THE [Arb] returned by this function.197    *198    * This needs to be a function because at time of writing, Kotlin 1.5's [Continuation] is single shot.199    * With arbs, we ideally need multishot. To rerun [builderFn], we need to "reset" the continuation.200    *201    * The current way we do it is to recreate a fresh [SingleShotArbContinuation] instance that202    * will provide another single shot Arb. Hence the reason why this function is invoked203    * on every call to [sample] / [edgecase].204    */205   private fun singleShotArb(mode: SingleShotGenerationMode, rs: RandomSource): Arb<A> {206      val restrictedContinuation = SingleShotArbContinuation.Restricted(mode, rs) {207         /**208          * At the end of the suspension we got a generated value [A] as a comprehension result.209          * This value can either be a sample, or an edgecase.210          */211         val value: A = builderFn(rs)212         /**213          * Here we point A into an Arb<A> with the appropriate enrichments including214          * [Shrinker], [Classifier], and [EdgecaseFn]. When edgecase returns null, we pass the generated value215          * to the edgecase function so to make sure we retain all arbs' edgecases inside the comprehension.216          */217         ArbitraryBuilder({ value }, classifier, shrinker, { rs -> edgecaseFn?.invoke(rs) ?: value }).build()218      }219      return with(restrictedContinuation) {220         this@with.createSingleShotArb()221      }222   }223}224/**225 * Creates a new suspendable [Arb] using [Continuation] using a stateless [fn].226 *227 * This function accepts an optional [shrinker], [classifier], and [edgecaseFn]. These parameters228 * will be passed to [ArbitraryBuilder].229 */230suspend fun <A> suspendArbitraryBuilder(231   shrinker: Shrinker<A>? = null,232   classifier: Classifier<A>? = null,233   edgecaseFn: EdgecaseFn<A>? = null,234   fn: suspend GenerateArbitraryBuilderContext.(RandomSource) -> A235): Arb<A> = suspendCoroutineUninterceptedOrReturn { cont ->236   val arb = object : Arb<A>() {237      override fun edgecase(rs: RandomSource): A? = singleShotArb(SingleShotGenerationMode.Edgecase, rs).edgecase(rs)238      override fun sample(rs: RandomSource): Sample<A> = singleShotArb(SingleShotGenerationMode.Sample, rs).sample(rs)239      override val classifier: Classifier<out A>? = classifier240      /**241       * This function generates a new instance of a single shot arb.242       * DO NOT CACHE THE [Arb] returned by this function.243       *244       * This needs to be a function because at time of writing, Kotlin 1.5's [Continuation] is single shot.245       * With arbs, we ideally need multishot. To rerun [fn], we need to "reset" the continuation.246       *247       * The current way we do it is to recreate a fresh [SingleShotArbContinuation] instance that248       * will provide another single shot Arb. Hence the reason why this function is invoked249       * on every call to [sample] / [edgecase].250       */251      private fun singleShotArb(genMode: SingleShotGenerationMode, rs: RandomSource): Arb<A> {252         val suspendableContinuation = SingleShotArbContinuation.Suspendedable(genMode, rs, cont.context) {253            /**254             * At the end of the suspension we got a generated value [A] as a comprehension result.255             * This value can either be a sample, or an edgecase.256             */257            val value: A = fn(rs)258            /**259             * Here we point A into an Arb<A> with the appropriate enrichments including260             * [Shrinker], [Classifier], and [EdgecaseFn]. When edgecase returns null, we pass the generated value261             * to the edgecase function so to make sure we retain all arbs' edgecases inside the comprehension.262             */263            ArbitraryBuilder({ value }, classifier, shrinker, { rs -> edgecaseFn?.invoke(rs) ?: value }).build()264         }265         return with(suspendableContinuation) {266            this@with.createSingleShotArb()267         }268      }269   }270   cont.resume(arb)271}272typealias SampleFn<A> = (RandomSource) -> A273typealias EdgecaseFn<A> = (RandomSource) -> A?274class ArbitraryBuilder<A>(275   private val sampleFn: SampleFn<A>,276   private val classifier: Classifier<A>?,277   private val shrinker: Shrinker<A>?,278   private val edgecaseFn: EdgecaseFn<A>?,279) {280   companion object {281      fun <A> create(f: (RandomSource) -> A): ArbitraryBuilder<A> = ArbitraryBuilder(f, null, null, null)282   }283   fun withClassifier(classifier: Classifier<A>) = ArbitraryBuilder(sampleFn, classifier, shrinker, edgecaseFn)284   fun withShrinker(shrinker: Shrinker<A>) = ArbitraryBuilder(sampleFn, classifier, shrinker, edgecaseFn)285   fun withEdgecaseFn(edgecaseFn: EdgecaseFn<A>) = ArbitraryBuilder(sampleFn, classifier, shrinker, edgecaseFn)286   fun withEdgecases(edgecases: List<A>) = ArbitraryBuilder(sampleFn, classifier, shrinker) {287      if (edgecases.isEmpty()) null else edgecases.random(it.random)288   }289   fun build() = object : Arb<A>() {290      override val classifier: Classifier<out A>? = this@ArbitraryBuilder.classifier291      override fun edgecase(rs: RandomSource): A? = edgecaseFn?.invoke(rs)292      override fun sample(rs: RandomSource): Sample<A> {293         val sample = sampleFn(rs)294         return if (shrinker == null) Sample(sample) else sampleOf(sample, shrinker)295      }296   }297}298interface BaseArbitraryBuilderSyntax {299   /**300    * [bind] returns the generated value of an arb. This can either be a sample or an edgecase.301    */302   suspend fun <T> Arb<T>.bind(): T303}304@RestrictsSuspension305interface ArbitraryBuilderContext : BaseArbitraryBuilderSyntax306interface GenerateArbitraryBuilderContext : BaseArbitraryBuilderSyntax307enum class SingleShotGenerationMode { Edgecase, Sample }308sealed class SingleShotArbContinuation<F : BaseArbitraryBuilderSyntax, A>(309   override val context: CoroutineContext,310   private val generationMode: SingleShotGenerationMode,311   private val randomSource: RandomSource,312   private val fn: suspend F.() -> Arb<A>313) : Continuation<Arb<A>>, BaseArbitraryBuilderSyntax {314   class Restricted<A>(315      genMode: SingleShotGenerationMode,316      rs: RandomSource,317      fn: suspend ArbitraryBuilderContext.() -> Arb<A>318   ) : SingleShotArbContinuation<ArbitraryBuilderContext, A>(EmptyCoroutineContext, genMode, rs, fn),319      ArbitraryBuilderContext320   class Suspendedable<A>(321      genMode: SingleShotGenerationMode,322      rs: RandomSource,323      override val context: CoroutineContext,324      fn: suspend GenerateArbitraryBuilderContext.() -> Arb<A>325   ) : SingleShotArbContinuation<GenerateArbitraryBuilderContext, A>(context, genMode, rs, fn),326      GenerateArbitraryBuilderContext327   private lateinit var returnedArb: Arb<A>328   private var hasExecuted: Boolean = false329   override fun resumeWith(result: Result<Arb<A>>) {330      hasExecuted = true331      result.map { resultArb -> returnedArb = resultArb }.getOrThrow()332   }333   override suspend fun <T> Arb<T>.bind(): T = when (generationMode) {334      SingleShotGenerationMode.Edgecase -> this.edgecase(randomSource) ?: this.sample(randomSource).value335      SingleShotGenerationMode.Sample -> this.sample(randomSource).value336   }337   /**338    * It's important to understand that at the time of writing (Kotlin 1.5) [Continuation] is single shot,339    * i.e. it can only be resumed once. When it's possible to create multishot continuations in the future, we340    * might be able to simplify this further.341    *342    * The aforementioned limitation means the [Arb] that we construct through this mechanism can only be used343    * to generate exactly one value. Hence, to recycle and rerun the specified composed transformation,344    * we need to recreate the [SingleShotArbContinuation] instance and call [createSingleShotArb] again.345    */346   fun F.createSingleShotArb(): Arb<A> {347      require(!hasExecuted) { "continuation has already been executed, if you see this error please raise a bug report" }348      val result = fn.startCoroutineUninterceptedOrReturn(this@createSingleShotArb, this@SingleShotArbContinuation)...

BuilderTest.kt

Source:BuilderTest.kt

...16import io.kotest.property.arbitrary.IntShrinker17import io.kotest.property.arbitrary.alphanumeric18import io.kotest.property.arbitrary.arbitrary19import io.kotest.property.arbitrary.constant20import io.kotest.property.arbitrary.edgecases21import io.kotest.property.arbitrary.flatMap22import io.kotest.property.arbitrary.generateArbitrary23import io.kotest.property.arbitrary.int24import io.kotest.property.arbitrary.map25import io.kotest.property.arbitrary.next26import io.kotest.property.arbitrary.numbers.IntClassifier27import io.kotest.property.arbitrary.single28import io.kotest.property.arbitrary.string29import io.kotest.property.arbitrary.take30import io.kotest.property.arbitrary.withEdgecases31import kotlinx.coroutines.withContext32import kotlin.coroutines.CoroutineContext33import kotlin.random.nextInt34class BuilderTest : FunSpec() {35   init {36      test("custom arb test") {37         arbitrary {38            it.random.nextInt(3..6)39         }.take(1000).toSet() shouldBe setOf(3, 4, 5, 6)40      }41      test("composition of arbs") {42         data class Person(val name: String, val age: Int)43         val personArb = arbitrary { rs ->44            val name = Arb.string(10..12).next(rs)45            val age = Arb.int(21, 150).next(rs)46            Person(name, age)47         }48         personArb.next().name.shouldHaveLengthBetween(10, 12)49         personArb.next().age.shouldBeBetween(21, 150)50      }51      context("arbitrary builder using restricted continuation") {52         test("should be stack safe") {53            val arb: Arb<Int> = arbitrary {54               (1..100000).map {55                  Arb.int().bind()56               }.last()57            }58            val result = shouldNotThrowAny { arb.single(RandomSource.seeded(1234)) }59            result shouldBe -148693402360         }61         test("should be equivalent to chaining flatMaps") {62            val arbFlatMaps: Arb<String> =63               Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").flatMap { first ->64                  Arb.int(1..9).withEdgecases(5).flatMap { second ->65                     Arb.int(101..109).withEdgecases(100 + second).map { third ->66                        "$first $second $third"67                     }68                  }69               }70            val arb: Arb<String> = arbitrary {71               val first = Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").bind()72               val second = Arb.int(1..9).withEdgecases(5).bind()73               val third = Arb.int(101..109).withEdgecases(100 + second).bind()74               "$first $second $third"75            }76            val flatMapsResult = arbFlatMaps.generate(RandomSource.seeded(12345L)).take(100).map { it.value }.toList()77            val builderResult = arb.generate(RandomSource.seeded(12345L)).take(100).map { it.value }.toList()78            // should be equivalent79            builderResult shouldContainExactly flatMapsResult80         }81         test("should bind edgecases") {82            val arb: Arb<String> = arbitrary {83               val first = Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").bind()84               val second = Arb.int(1..9).withEdgecases(5).bind()85               val third = Arb.int(101..109).withEdgecases(100 + second, 109).bind()86               "$first $second $third"87            }88            arb.edgecases() shouldContainExactlyInAnyOrder setOf(89               "edge1 5 105",90               "edge2 5 105",91               "edge1 5 109",92               "edge2 5 109",93            )94         }95         test("should preserve edgecases of dependent arbs, even when intermideary arb(s) have no edgecases") {96            val arb: Arb<String> = arbitrary {97               val first = Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").bind()98               val second = Arb.int(1..4).withEdgecases(emptyList()).bind()99               val third = Arb.int(101..109).withEdgecases(100 + second).bind()100               "$first $second $third"101            }102            arb.edgecases() shouldContainExactlyInAnyOrder setOf(103               "edge1 1 101",104               "edge1 2 102",105               "edge1 3 103",106               "edge1 4 104",107               "edge2 1 101",108               "edge2 2 102",109               "edge2 3 103",110               "edge2 4 104"111            )112         }113         test("should assign edgecases") {114            val edges = setOf("edge1", "edge2")115            val arb = arbitrary(edges.toList()) { "abcd" }116            arb.edgecases() shouldContainExactlyInAnyOrder edges117         }118         test("should assign edgecases and shrinker") {119            val shrinker = IntShrinker(1..5)120            val edges = setOf(1, 2)121            val arb = arbitrary(edges.toList(), shrinker) { 5 }122            arb.edgecases() shouldContainExactlyInAnyOrder edges123            arb.sample(RandomSource.seeded(1234L)).shrinks.children.value.map { it.value() } shouldBe shrinker.shrink(5)124         }125         test("should use shrinker when provided") {126            val shrinker = IntShrinker(1..5)127            val arb = arbitrary(shrinker) { 5 }128            arb.classifier.shouldBeNull()129            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks130            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(5)131         }132         test("should use classifier when provided") {133            val classifier = IntClassifier(1..5)134            val arb = arbitrary(classifier) { 5 }135            arb.classifier shouldBeSameInstanceAs classifier136         }137         test("should use classifier and shrinker when provided") {138            val shrinker = IntShrinker(1..5)139            val classifier = IntClassifier(1..5)140            val arb = arbitrary(shrinker, classifier) { 5 }141            arb.classifier shouldBeSameInstanceAs classifier142            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks143            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(5)144         }145         test("should use edgecase function when provided") {146            val arb = arbitrary({ 5 }) { 10 }147            arb.edgecases() shouldContainExactlyInAnyOrder setOf(5)148         }149         test("should use edgecase function and shrinker when provided") {150            val shrinker = IntShrinker(1..5)151            val arb = arbitrary({ 5 }, shrinker) { 10 }152            arb.edgecases() shouldContainExactlyInAnyOrder setOf(5)153            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks154            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(10)155         }156         test("should support .bind() syntax") {157            val arb = Arb.constant(5)158            val shrinker = IntShrinker(1..5)159            val classifier = IntClassifier(1..5)160            arbitrary { arb.bind() }.single() shouldBe 5161            arbitrary(shrinker) { arb.bind() }.single() shouldBe 5162            arbitrary(classifier) { arb.bind() }.single() shouldBe 5163            arbitrary(shrinker, classifier) { arb.bind() }.single() shouldBe 5164            arbitrary(listOf(5)) { arb.bind() }.single() shouldBe 5165            arbitrary({ 5 }) { arb.bind() }.single() shouldBe 5166            arbitrary({ 5 }, shrinker) { arb.bind() }.single() shouldBe 5167         }168      }169      context("suspend arbitrary builder with unrestricted continuation") {170         suspend fun combineAsString(vararg values: Any?): String = values.joinToString(" ")171         test("should build arb on the parent coroutine context") {172            val arb = withContext(Foo("hello")) {173               generateArbitrary {174                  val hello = coroutineContext[Foo]?.value175                  val world = arbitrary { "world" }.bind()176                  val first = Arb.int(1..10).bind()177                  val second = Arb.int(11..20).bind()178                  combineAsString(hello, world, first, second)179               }180            }181            arb.generate(RandomSource.seeded(1234L)).take(4).toList().map { it.value } shouldContainExactly listOf(182               "hello world 2 20",183               "hello world 6 12",184               "hello world 7 19",185               "hello world 9 13"186            )187         }188         test("should bind edgecases") {189            val arb: Arb<String> = generateArbitrary {190               val first = Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").bind()191               val second = Arb.int(1..9).withEdgecases(5).bind()192               val third = Arb.int(101..109).withEdgecases(100 + second, 109).bind()193               combineAsString(first, second, third)194            }195            arb.edgecases() shouldContainExactlyInAnyOrder setOf(196               "edge1 5 105",197               "edge2 5 105",198               "edge1 5 109",199               "edge2 5 109",200            )201         }202         test("should preserve edgecases of dependent arbs, even when intermideary arb(s) have no edgecases") {203            val arb: Arb<String> = generateArbitrary {204               val first = Arb.string(5, Codepoint.alphanumeric()).withEdgecases("edge1", "edge2").bind()205               val second = Arb.int(1..4).withEdgecases(emptyList()).bind()206               val third = Arb.int(101..109).withEdgecases(100 + second).bind()207               combineAsString(first, second, third)208            }209            arb.edgecases() shouldContainExactlyInAnyOrder setOf(210               "edge1 1 101",211               "edge1 2 102",212               "edge1 3 103",213               "edge1 4 104",214               "edge2 1 101",215               "edge2 2 102",216               "edge2 3 103",217               "edge2 4 104"218            )219         }220         test("should propagate exception") {221            val throwingArb = generateArbitrary {222               val number = Arb.int(1..4).withEdgecases(emptyList()).bind()223               // try to throw something inside the arb224               number shouldBeGreaterThan 5225            }226            val assertionError = shouldThrow<AssertionError> { execute(RandomSource.seeded(1234L), throwingArb) }227            assertionError.message shouldBe "4 should be > 5"228         }229         test("should assign edgecases") {230            val edges = setOf("edge1", "edge2")231            val arb = generateArbitrary(edges.toList()) { "abcd" }232            arb.edgecases() shouldContainExactlyInAnyOrder edges233         }234         test("should assign edgecases and shrinker") {235            val shrinker = IntShrinker(1..5)236            val edges = setOf(1, 2)237            val arb = generateArbitrary(edges.toList(), shrinker) { 5 }238            arb.edgecases() shouldContainExactlyInAnyOrder edges239            arb.sample(RandomSource.seeded(1234L)).shrinks.children.value.map { it.value() } shouldBe shrinker.shrink(5)240         }241         test("should use shrinker when provided") {242            val shrinker = IntShrinker(1..5)243            val arb = generateArbitrary(shrinker) { 5 }244            arb.classifier.shouldBeNull()245            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks246            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(5)247         }248         test("should use classifier when provided") {249            val classifier = IntClassifier(1..5)250            val arb = generateArbitrary(classifier) { 5 }251            arb.classifier shouldBeSameInstanceAs classifier252         }253         test("should use classifier and shrinker when provided") {254            val shrinker = IntShrinker(1..5)255            val classifier = IntClassifier(1..5)256            val arb = generateArbitrary(shrinker, classifier) { 5 }257            arb.classifier shouldBeSameInstanceAs classifier258            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks259            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(5)260         }261         test("should use edgecase function when provided") {262            val arb = generateArbitrary({ 5 }) { 10 }263            arb.edgecases() shouldContainExactlyInAnyOrder setOf(5)264         }265         test("should use edgecase function and shrinker when provided") {266            val shrinker = IntShrinker(1..5)267            val arb = generateArbitrary({ 5 }, shrinker) { 10 }268            arb.edgecases() shouldContainExactlyInAnyOrder setOf(5)269            val shrinks = arb.sample(RandomSource.seeded(1234L)).shrinks270            shrinks.children.value.map { it.value() } shouldContainExactly shrinker.shrink(10)271         }272         test("should support .bind() syntax") {273            val arb = Arb.constant(5)274            val shrinker = IntShrinker(1..5)275            val classifier = IntClassifier(1..5)276            generateArbitrary { arb.bind() }.single() shouldBe 5277            generateArbitrary(shrinker) { arb.bind() }.single() shouldBe 5278            generateArbitrary(classifier) { arb.bind() }.single() shouldBe 5279            generateArbitrary(shrinker, classifier) { arb.bind() }.single() shouldBe 5280            generateArbitrary(listOf(5)) { arb.bind() }.single() shouldBe 5281            generateArbitrary({ 5 }) { arb.bind() }.single() shouldBe 5282            generateArbitrary({ 5 }, shrinker) { arb.bind() }.single() shouldBe 5...

bind.kt

Source:bind.kt

...432   val arbL = genL.toArb()433   val arbM = genM.toArb()434   val arbN = genN.toArb()435   return object : Arb<T>() {436      override fun edgecase(rs: RandomSource): T? {437         return bindFn(438            arbA.edgecase(rs) ?: arbA.next(rs),439            arbB.edgecase(rs) ?: arbB.next(rs),440            arbC.edgecase(rs) ?: arbC.next(rs),441            arbD.edgecase(rs) ?: arbD.next(rs),442            arbE.edgecase(rs) ?: arbE.next(rs),443            arbF.edgecase(rs) ?: arbF.next(rs),444            arbG.edgecase(rs) ?: arbG.next(rs),445            arbH.edgecase(rs) ?: arbH.next(rs),446            arbI.edgecase(rs) ?: arbI.next(rs),447            arbJ.edgecase(rs) ?: arbJ.next(rs),448            arbK.edgecase(rs) ?: arbK.next(rs),449            arbL.edgecase(rs) ?: arbL.next(rs),450            arbM.edgecase(rs) ?: arbM.next(rs),451            arbN.edgecase(rs) ?: arbN.next(rs),452         )453      }454      override fun sample(rs: RandomSource): Sample<T> {455         val (av, ar) = arbA.sample(rs)456         val (bv, br) = arbB.sample(rs)457         val (cv, cr) = arbC.sample(rs)458         val (dv, dr) = arbD.sample(rs)459         val (ev, er) = arbE.sample(rs)460         val (fv, fr) = arbF.sample(rs)461         val (gv, gr) = arbG.sample(rs)462         val (hv, hr) = arbH.sample(rs)463         val (iv, ir) = arbI.sample(rs)464         val (jv, jr) = arbJ.sample(rs)465         val (kv, kr) = arbK.sample(rs)...

map.kt

Source:map.kt

...7 * Returns a new [Arb] which takes its elements from the receiver and maps them using the supplied function.8 */9fun <A, B> Arb<A>.map(fn: (A) -> B): Arb<B> = trampoline { sampleA ->10   object : Arb<B>() {11      override fun edgecase(rs: RandomSource): B? = fn(sampleA.value)12      override fun sample(rs: RandomSource): Sample<B> {13         val value = fn(sampleA.value)14         val shrinks = sampleA.shrinks.map(fn)15         return Sample(value, shrinks)16      }17   }18}19/**20 * Returns a new [Arb] which takes its elements from the receiver and maps them using the supplied function.21 */22fun <A, B> Arb<A>.flatMap(fn: (A) -> Arb<B>): Arb<B> = trampoline { fn(it.value) }23/**24 * Returns a new [TrampolineArb] from the receiver [Arb] which composes the operations of [next] lambda25 * using a trampoline method. This allows [next] function to be executed without exhausting call stack.26 */27internal fun <A, B> Arb<A>.trampoline(next: (Sample<A>) -> Arb<B>): Arb<B> = when (this) {28   is TrampolineArb -> this.thunk(next)29   else -> TrampolineArb(this).thunk(next)30}31/**32 * The [TrampolineArb] is a special Arb that exchanges call stack with heap.33 * In a nutshell, this arb stores command chains to be applied to the original arb inside a list.34 * This technique is an imperative reduction of Free Monads. This eliminates the need of creating intermediate35 * Trampoline Monad and tail-recursive function on those which can be expensive.36 * This minimizes the amount of code and unnecessary object allocation during sample generation in the expense of typesafety.37 *38 * This is an internal implementation. Do not use this TrampolineArb as is and please do not expose this39 * to users outside of the library. For library maintainers, please use the [Arb.trampoline] extension function.40 * The extension function will provide some type-guardrails to workaround the loss of types within this Arb.41 */42@Suppress("UNCHECKED_CAST")43internal class TrampolineArb<A> private constructor(44   private val first: Arb<A>,45   private val commands: List<(Sample<Any>) -> Arb<Any>>46) : Arb<A>() {47   constructor(first: Arb<A>) : this(first, emptyList())48   fun <A, B> thunk(fn: (Sample<A>) -> Arb<B>): TrampolineArb<B> =49      TrampolineArb(50         first,51         commands + (fn as (Sample<Any>) -> Arb<Any>)52      ) as TrampolineArb<B>53   override fun edgecase(rs: RandomSource): A? =54      commands55         .fold(first as Arb<Any>) { currentArb, next ->56            val currentEdge = currentArb.edgecase(rs) ?: currentArb.sample(rs).value57            next(Sample(currentEdge))58         }59         .edgecase(rs) as A?60   override fun sample(rs: RandomSource): Sample<A> =61      commands62         .fold(first as Arb<Any>) { currentArb, next ->63            next(currentArb.sample(rs))64         }65         .sample(rs) as Sample<A>66}...

FilterTest.kt

Source:FilterTest.kt

...25   }26   test("should filter edge cases") {27      val arb = Arb.int(1..10).withEdgecases(1, 2, 3).filter { it % 2 == 0 }28      val edgeCases = arb29         .generate(RandomSource.seeded(1234L), EdgeConfig(edgecasesGenerationProbability = 1.0))30         .take(5)31         .map { it.value }32         .toList()33      edgeCases shouldContainExactly listOf(2, 2, 2, 2, 2)34   }35   test("should be stack safe") {36      val arb = object : Arb<Int>() {37         override fun edgecase(rs: RandomSource): Int? = null38         override fun sample(rs: RandomSource): Sample<Int> = Sample(rs.random.nextInt())39      }40      shouldNotThrow<StackOverflowError> {41         arb.filter { it % 2 == 0 }.take(1000000).toList()42      }43   }44   test("should apply filter to shrinks") {45      val arbEvenInts = Arb.int(-100..100).filter { it % 2 == 0 }46      val oddNumbers = (-100..100).filter { it % 2 != 0 }47      arbEvenInts.samples().take(100).forAll { sample ->48         sample.shrinks.value() shouldNotBeIn oddNumbers49         sample.shrinks.children.value.forAll {50            it.value() shouldNotBeIn oddNumbers51         }...

identifierGenerator.kt

Source:identifierGenerator.kt

...24import kotlinx.collections.immutable.PersistentList25import kotlinx.collections.immutable.toPersistentList26internal fun Arb.Companion.semVerIdentifier(minParts: Int = 1, maxParts: Int): Arb<Pair<PersistentList<Identifier>, String>> =27    object : Arb<Pair<PersistentList<Identifier>, String>>() {28        override fun edgecase(rs: RandomSource): Pair<PersistentList<Identifier>, String>? = null29        override fun sample(rs: RandomSource): Sample<Pair<PersistentList<Identifier>, String>> {30            // I don't really know what a sensible maxSize would be, even 100 feels a bit large for a semver identifier31            // the system should be able to handle identifiers of any size (as long as the final string isn't larger32            // than what is supported by the JVM)33            val stringArb = Arb.string(minSize = 1, maxSize = 100, codepoints = Codepoint.semVerIdentifier())34            val sequenceSize = rs.random.nextInt(minParts, maxParts + 1)35            val identifiers = stringArb.samples(rs)36                .take(sequenceSize)37                .map { it.value }38                .map { Identifier.of(it) }39                .toPersistentList()40            val identifierTextSequence = identifiers.joinToString(separator = ".")41            return Sample(identifiers to identifierTextSequence)42        }...

edgecases.kt

Source:edgecases.kt

...7 * Randomly chooses an [Arb] and then generates an edge case from that [Arb].8 * If the chosen arb has no edge cases, then another arb will be chosen.9 * If all [Arb]s have no edge cases, then returns null.10 */11tailrec fun <A> List<Arb<A>>.edgecase(rs: RandomSource): A? {12   if (this.isEmpty()) return null13   val shuffled = this.shuffled(rs.random)14   return when (val edge = shuffled.first().edgecase(rs)) {15      null -> this.drop(1).edgecase(rs)16      else -> edge17   }18}19/**20 * Collects the edge cases from this arb.21 * Will stop after the given number of iterations.22 * This function is mainly used for testing.23 */24fun <A> Arb<A>.edgecases(iterations: Int = 100, rs: RandomSource = RandomSource.default()): Set<A> =25   generate(rs, EdgeConfig(edgecasesGenerationProbability = 1.0))26      .take(iterations)27      .map { it.value }28      .toSet()29/**30 * Returns a new [Arb] with the supplied edge cases replacing any existing edge cases.31 */32fun <A> Arb<A>.withEdgecases(edgecases: List<A>): Arb<A> = arbitrary(edgecases) { this@withEdgecases.next(it) }33/**34 * Returns a new [Arb] with the supplied edge cases replacing any existing edge cases.35 */36fun <A> Arb<A>.withEdgecases(vararg edgecases: A): Arb<A> = this.withEdgecases(edgecases.toList())37fun <A> Arb<A>.removeEdgecases(): Arb<A> = this.withEdgecases(emptyList())38/**39 * Returns a new [Arb] with the edge cases from this arb transformed by the given function [f].40 */41fun <A> Arb<A>.modifyEdgecases(f: (A) -> A?): Arb<A> = object : Arb<A>() {42   override fun edgecase(rs: RandomSource): A? = this@modifyEdgecases.edgecase(rs)?.let(f)43   override fun sample(rs: RandomSource): Sample<A> = this@modifyEdgecases.sample(rs)44}...

arbs.kt

Source:arbs.kt

...24 **/25fun <A> Arb.Companion.lazy(f: () -> Arb<A>): Arb<A> {26   val arb by kotlin.lazy { f() }27   return object : Arb<A>() {28      override fun edgecase(rs: RandomSource): A? = arb.edgecase(rs)29      override fun sample(rs: RandomSource): Sample<A> = arb.sample(rs)30   }31}...

edgecase

Using AI Code Generation

1fun <T> Arb.Companion.edgecase(values: List<T>): Arb<T> =2if (values.isEmpty()) Arb.empty()3else Arb.from(values)4fun <T> Arb.Companion.edgecase(vararg values: T): Arb<T> =5if (values.isEmpty()) Arb.empty()6else Arb.from(values.toList())7fun <T> Arb.Companion.edgecase(values: Set<T>): Arb<T> =8if (values.isEmpty()) Arb.empty()9else Arb.from(values)10fun <K, V> Arb.Companion.edgecaseMap(keys: List<K>, values: List<V>): Arb<Map<K, V>> =11if (keys.isEmpty()) Arb.empty()12else Arb.from(EdgeCaseMapGenerator(keys, values))13fun <K, V> Arb.Companion.edgecaseMap(keys: Set<K>, values: List<V>): Arb<Map<K, V>> =14if (keys.isEmpty()) Arb.empty()15else Arb.from(EdgeCaseMapGenerator(keys.toList(), values))16fun <K, V> Arb.Companion.edgecaseMap(keys: List<K>, values: Set<V>): Arb<Map<K, V>> =17if (keys.isEmpty()) Arb.empty()18else Arb.from(EdgeCaseMapGenerator(keys, values.toList()))

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