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How to use Arb.Companion.string method of io.kotest.property.arbitrary.StringShrinkerWithMin class

Best Kotest code snippet using io.kotest.property.arbitrary.StringShrinkerWithMin.Arb.Companion.string

strings.kt

Source:strings.kt

1package io.kotest.property.arbitrary2import io.kotest.property.Arb3import io.kotest.property.Shrinker4import io.kotest.property.arbitrary.strings.StringClassifier5import kotlin.random.nextInt6/**7 * Returns an [Arb] where each random value is a String of length between minSize and maxSize.8 * By default, the arb uses a [ascii] codepoint generator, but this can be substituted9 * with any codepoint generator. There are many available, such as [katakana] and so on.10 *11 * The edge case values are a string of min length, using the first12 * edge case codepoint provided by the codepoints arb. If the min length is 0 and maxSize > 0, then13 * the edge cases will include a string of length 1 as well.14 */15fun Arb.Companion.string(16   minSize: Int = 0,17   maxSize: Int = 100,18   codepoints: Arb<Codepoint> = Codepoint.ascii()19): Arb<String> {20   return ArbitraryBuilder.create { rs ->21      val size = rs.random.nextInt(minSize..maxSize)22      codepoints.take(size, rs).joinToString("") { it.asString() }23   }.withEdgecaseFn { rs ->24      if (minSize == maxSize) null else {25         val lowCodePoint = codepoints.edgecase(rs)26         val min = lowCodePoint?.let { cp -> List(minSize) { cp.asString() }.joinToString("") }27         val minPlus1 = lowCodePoint?.let { cp -> List(minSize + 1) { cp.asString() }.joinToString("") }28         val edgeCases = listOfNotNull(min, minPlus1)29            .filter { it.length in minSize..maxSize }30         if (edgeCases.isEmpty()) null else edgeCases.random(rs.random)31      }32   }.withShrinker(StringShrinkerWithMin(minSize))33      .withClassifier(StringClassifier(minSize, maxSize))34      .build()35}36/**37 * Returns an [Arb] where each random value is a String which has a length in the given range.38 * By default the arb uses a [ascii] codepoint generator, but this can be substituted39 * with any codepoint generator. There are many available, such as [katakana] and so on.40 *41 * The edge case values are a string of the first value in the range, using the first edge case42 * codepoint provided by the codepoints arb.43 */44fun Arb.Companion.string(range: IntRange, codepoints: Arb<Codepoint> = Codepoint.ascii()): Arb<String> =45   Arb.string(range.first, range.last, codepoints)46/**47 * Returns an [Arb] where each random value is a String of length [size].48 * By default the arb uses a [ascii] codepoint generator, but this can be substituted49 * with any codepoint generator. There are many available, such as [katakana] and so on.50 *51 * There are no edge case values associated with this arb.52 */53fun Arb.Companion.string(size: Int, codepoints: Arb<Codepoint> = Codepoint.ascii()): Arb<String> =54   Arb.string(size, size, codepoints)55@Deprecated("This Shrinker does not take into account string lengths. Use StringShrinkerWithMin. This was deprecated in 4.5.")56object StringShrinker : Shrinker<String> {57   override fun shrink(value: String): List<String> {58      return when {59         value == "" -> emptyList()60         value == "a" -> listOf("")61         value.length == 1 -> listOf("", "a")62         else -> {63            val firstHalf = value.take(value.length / 2 + value.length % 2)64            val secondHalf = value.takeLast(value.length / 2)65            val secondHalfAs = firstHalf.padEnd(value.length, 'a')66            val firstHalfAs = secondHalf.padStart(value.length, 'a')67            val dropFirstChar = value.drop(1)68            val dropLastChar = value.dropLast(1)69            listOf(70               firstHalf,71               firstHalfAs,72               secondHalf,73               secondHalfAs,74               dropFirstChar,75               dropLastChar76            )77         }78      }79   }80}81/**82 * Shrinks a string. Shrunk variants will be shorter and simplified.83 *84 * Shorter strings will be at least [minLength] in length.85 *86 * Simplified strings will have characters replaced by a character (selected by [simplestCharSelector])87 * of each pre-shrunk value. By default, this is the first character of the pre-shrunk string.88 *89 * When [simplestCharSelector] returns null, no simpler variants will be created.90 */91class StringShrinkerWithMin(92   private val minLength: Int = 0,93   private val simplestCharSelector: (preShrinkValue: String) -> Char? = CharSequence::firstOrNull94) : Shrinker<String> {95//   @Deprecated("a static 'simplestChar' means invalid shrinks can be generated - use the alternative constructor instead, which allows for a dynamic 'simplestChar'")96//   constructor (97//      minLength: Int = 0,98//      simplestChar: Char,99//   ) : this(minLength, { simplestChar })100   override fun shrink(value: String): List<String> {101      val simplestChar: Char? = simplestCharSelector(value)102      val isShortest = value.length == minLength103      val isSimplest = value.all { it == simplestChar }104      return buildList {105         if (!isShortest) {106            addAll(shorterVariants(value))107         }108         if (!isSimplest && simplestChar != null) {109            addAll(simplerVariants(value, simplestChar))110         }111      }.mapNotNull {112         // ensure the variants are at least minLength long113         when {114            simplestChar != null -> it.padEnd(minLength, simplestChar)115            it.length >= minLength -> it116            else -> null // this string is too short, so filter it out117         }118      }.distinct()119   }120   private fun simplerVariants(value: String, simplestChar: Char): List<String> =121      listOfNotNull(122         // replace the first and last chars that aren't simplestChar with simplestChar123         replace(value, simplestChar, value.indexOfFirst { it != simplestChar }),124         replace(value, simplestChar, value.indexOfLast { it != simplestChar }),125      )126   private fun shorterVariants(value: String) =127      listOf(128         value.take(value.length / 2 + value.length % 2),129         value.takeLast(value.length / 2),130         value.drop(1),131         value.dropLast(1),132      )133   private fun replace(value: String, newChar: Char, index: Int) =134      if (index == -1) null else value.replaceRange(index..index, newChar.toString())135}...

Arb.Companion.string

Using AI Code Generation

1import io.kotest.core.spec.style.FunSpec2import io.kotest.matchers.shouldBe3import io.kotest.property.Arb4import io.kotest.property.arbitrary.string5import io.kotest.property.checkAll6class StringShrinkerWithMinUnitTest : FunSpec({7    test("should shrink the input") {8        checkAll(Arb.Companion.string(0, 4)) {9        }10    }11})

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