KaneAI - World’s First E2E Software Testing Agent.Book a Demo Join TestMu Conference

How to use rawShrinkValue method in fast-check-monorepo

Best JavaScript code snippet using fast-check-monorepo

FrequencyArbitrary.ts

Source:FrequencyArbitrary.ts

1import { Random } from '../../random/generator/Random';2import { Stream } from '../../stream/Stream';3import { Arbitrary } from '../../check/arbitrary/definition/Arbitrary';4import { Value } from '../../check/arbitrary/definition/Value';5import { DepthContext, DepthIdentifier, getDepthContextFor } from './helpers/DepthContext';6import { depthBiasFromSizeForArbitrary, DepthSize } from './helpers/MaxLengthFromMinLength';7import { safePush } from '../../utils/globals';8const safePositiveInfinity = Number.POSITIVE_INFINITY;9const safeMaxSafeInteger = Number.MAX_SAFE_INTEGER;10const safeNumberIsInteger = Number.isInteger;11const safeMathFloor = Math.floor;12const safeMathPow = Math.pow;13const safeMathMin = Math.min;14/** @internal */15export class FrequencyArbitrary<T> extends Arbitrary<T> {16  readonly cumulatedWeights: number[];17  readonly totalWeight: number;18  static from<T>(warbs: _WeightedArbitrary<T>[], constraints: _Constraints, label: string): Arbitrary<T> {19    if (warbs.length === 0) {20      throw new Error(`${label} expects at least one weighted arbitrary`);21    }22    let totalWeight = 0;23    for (let idx = 0; idx !== warbs.length; ++idx) {24      const currentArbitrary = warbs[idx].arbitrary;25      if (currentArbitrary === undefined) {26        throw new Error(`${label} expects arbitraries to be specified`);27      }28      const currentWeight = warbs[idx].weight;29      totalWeight += currentWeight;30      if (!safeNumberIsInteger(currentWeight)) {31        throw new Error(`${label} expects weights to be integer values`);32      }33      if (currentWeight < 0) {34        throw new Error(`${label} expects weights to be superior or equal to 0`);35      }36    }37    if (totalWeight <= 0) {38      throw new Error(`${label} expects the sum of weights to be strictly superior to 0`);39    }40    const sanitizedConstraints: _SanitizedConstraints = {41      depthBias: depthBiasFromSizeForArbitrary(constraints.depthSize, constraints.maxDepth !== undefined),42      maxDepth: constraints.maxDepth != undefined ? constraints.maxDepth : safePositiveInfinity,43      withCrossShrink: !!constraints.withCrossShrink,44    };45    return new FrequencyArbitrary(warbs, sanitizedConstraints, getDepthContextFor(constraints.depthIdentifier));46  }47  private constructor(48    readonly warbs: _WeightedArbitrary<T>[],49    readonly constraints: _SanitizedConstraints,50    readonly context: DepthContext51  ) {52    super();53    let currentWeight = 0;54    this.cumulatedWeights = [];55    for (let idx = 0; idx !== warbs.length; ++idx) {56      currentWeight += warbs[idx].weight;57      safePush(this.cumulatedWeights, currentWeight);58    }59    this.totalWeight = currentWeight;60  }61  generate(mrng: Random, biasFactor: number | undefined): Value<T> {62    if (this.mustGenerateFirst()) {63      // index=0 can be selected even if it has a weight equal to zero64      return this.safeGenerateForIndex(mrng, 0, biasFactor);65    }66    const selected = mrng.nextInt(this.computeNegDepthBenefit(), this.totalWeight - 1);67    for (let idx = 0; idx !== this.cumulatedWeights.length; ++idx) {68      if (selected < this.cumulatedWeights[idx]) {69        return this.safeGenerateForIndex(mrng, idx, biasFactor);70      }71    }72    throw new Error(`Unable to generate from fc.frequency`);73  }74  canShrinkWithoutContext(value: unknown): value is T {75    return this.canShrinkWithoutContextIndex(value) !== -1;76  }77  shrink(value: T, context?: unknown): Stream<Value<T>> {78    if (context !== undefined) {79      const safeContext = context as _FrequencyArbitraryContext<T>;80      const selectedIndex = safeContext.selectedIndex;81      const originalBias = safeContext.originalBias;82      const originalArbitrary = this.warbs[selectedIndex].arbitrary;83      const originalShrinks = originalArbitrary84        .shrink(value, safeContext.originalContext)85        .map((v) => this.mapIntoValue(selectedIndex, v, null, originalBias));86      if (safeContext.clonedMrngForFallbackFirst !== null) {87        if (safeContext.cachedGeneratedForFirst === undefined) {88          safeContext.cachedGeneratedForFirst = this.safeGenerateForIndex(89            safeContext.clonedMrngForFallbackFirst,90            0,91            originalBias92          );93        }94        const valueFromFirst = safeContext.cachedGeneratedForFirst;95        return Stream.of(valueFromFirst).join(originalShrinks);96      }97      return originalShrinks;98    }99    const potentialSelectedIndex = this.canShrinkWithoutContextIndex(value);100    if (potentialSelectedIndex === -1) {101      return Stream.nil(); // No arbitrary found to accept this value102    }103    return this.defaultShrinkForFirst(potentialSelectedIndex).join(104      this.warbs[potentialSelectedIndex].arbitrary105        .shrink(value, undefined) // re-checked by canShrinkWithoutContextIndex106        .map((v) => this.mapIntoValue(potentialSelectedIndex, v, null, undefined))107    );108  }109  /** Generate shrink values for first arbitrary when no context and no value was provided */110  private defaultShrinkForFirst(selectedIndex: number): Stream<Value<T>> {111    ++this.context.depth; // increase depth112    try {113      if (!this.mustFallbackToFirstInShrink(selectedIndex) || this.warbs[0].fallbackValue === undefined) {114        // Not applicable: no fallback to first arbitrary on shrink OR no hint to shrink without an initial value and context115        return Stream.nil();116      }117    } finally {118      --this.context.depth; // decrease depth (reset depth)119    }120    // The arbitrary at [0] accepts to shrink fallbackValue.default without any context (context=undefined)121    const rawShrinkValue = new Value(this.warbs[0].fallbackValue.default, undefined);122    return Stream.of(this.mapIntoValue(0, rawShrinkValue, null, undefined));123  }124  /** Extract the index of the generator that would have been able to gennrate the value */125  private canShrinkWithoutContextIndex(value: unknown): number {126    if (this.mustGenerateFirst()) {127      return this.warbs[0].arbitrary.canShrinkWithoutContext(value) ? 0 : -1;128    }129    try {130      ++this.context.depth; // increase depth131      for (let idx = 0; idx !== this.warbs.length; ++idx) {132        const warb = this.warbs[idx];133        if (warb.weight !== 0 && warb.arbitrary.canShrinkWithoutContext(value)) {134          return idx;135        }136      }137      return -1;138    } finally {139      --this.context.depth; // decrease depth (reset depth)140    }141  }142  /** Map the output of one of the children with the context of frequency */143  private mapIntoValue(144    idx: number,145    value: Value<T>,146    clonedMrngForFallbackFirst: Random | null,147    biasFactor: number | undefined148  ): Value<T> {149    const context: _FrequencyArbitraryContext<T> = {150      selectedIndex: idx,151      originalBias: biasFactor,152      originalContext: value.context,153      clonedMrngForFallbackFirst,154    };155    return new Value(value.value, context);156  }157  /** Generate using Arbitrary at index idx and safely handle depth context */158  private safeGenerateForIndex(mrng: Random, idx: number, biasFactor: number | undefined): Value<T> {159    ++this.context.depth; // increase depth160    try {161      const value = this.warbs[idx].arbitrary.generate(mrng, biasFactor);162      const clonedMrngForFallbackFirst = this.mustFallbackToFirstInShrink(idx) ? mrng.clone() : null;163      return this.mapIntoValue(idx, value, clonedMrngForFallbackFirst, biasFactor);164    } finally {165      --this.context.depth; // decrease depth (reset depth)166    }167  }168  /** Check if generating a value based on the first arbitrary is compulsory */169  private mustGenerateFirst(): boolean {170    return this.constraints.maxDepth <= this.context.depth;171  }172  /** Check if fallback on first arbitrary during shrinking is required */173  private mustFallbackToFirstInShrink(idx: number): boolean {174    return idx !== 0 && this.constraints.withCrossShrink && this.warbs[0].weight !== 0;175  }176  /** Compute the benefit for the current depth */177  private computeNegDepthBenefit(): number {178    const depthBias = this.constraints.depthBias;179    if (depthBias <= 0 || this.warbs[0].weight === 0) {180      return 0;181    }182    // We use a pow-based biased benefit as the deeper we go the more chance we have183    // to encounter thousands of instances of the current arbitrary.184    const depthBenefit = safeMathFloor(safeMathPow(1 + depthBias, this.context.depth)) - 1;185    // -0 has to be converted into 0 thus we call ||0186    return -safeMathMin(this.totalWeight * depthBenefit, safeMaxSafeInteger) || 0;187  }188}189/** @internal */190export type _Constraints = {191  withCrossShrink?: boolean;192  depthSize?: DepthSize;193  maxDepth?: number;194  depthIdentifier?: DepthIdentifier | string;195};196/** @internal */197type _SanitizedConstraints = {198  withCrossShrink: boolean;199  depthBias: number;200  maxDepth: number;201};202/** @internal */203interface _WeightedArbitrary<T> {204  weight: number;205  arbitrary: Arbitrary<T>;206  // If specified, the arbitrary must accept to shrink fallbackValue.default without any context207  fallbackValue?: { default: T };208}209/** @internal */210type _FrequencyArbitraryContext<T> = {211  selectedIndex: number;212  originalBias: number | undefined;213  originalContext: unknown;214  clonedMrngForFallbackFirst: Random | null;215  cachedGeneratedForFirst?: Value<T>;...

Using AI Code Generation

1const fc = require('fast-check');2const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/ArbitraryWithShrink');3const { integer } = require('fast-check/lib/check/arbitrary/IntegerArbitrary');4const arb = integer(0, 1000);5const value = 500;6const shrinks = rawShrinkValue(arb, value);7console.log(shrinks);8const fc = require('fast-check');9const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/ArbitraryWithShrink');10const { integer } = require('fast-check/lib/check/arbitrary/IntegerArbitrary');11const arb = integer(0, 1000);12const value = 500;13const shrinks = rawShrinkValue(arb, value);14console.log(shrinks);15const fc = require('fast-check');16const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/ArbitraryWithShrink');17const { integer } = require('fast-check/lib/check/arbitrary/IntegerArbitrary');18const arb = integer(0, 1000);19const value = 500;20const shrinks = rawShrinkValue(arb, value);21console.log(shrinks);22const fc = require('fast-check');23const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/ArbitraryWithShrink');24const { integer } = require('fast-check/lib/check/arbitrary/IntegerArbitrary');25const arb = integer(0, 1000);26const value = 500;27const shrinks = rawShrinkValue(arb, value);28console.log(shrinks);29const fc = require('fast-check');30const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/ArbitraryWithShrink');31const { integer } = require('fast-check/lib/check/arbitrary/IntegerArbitrary');32const arb = integer(0, 1000);33const value = 500;34const shrinks = rawShrinkValue(arb, value);35console.log(shrinks

Using AI Code Generation

1const fc = require("fast-check");2const { rawShrinkValue } = require("fast-check/lib/check/arbitrary/definition/Shrinkable");3const { nat } = require("fast-check/lib/check/arbitrary/NatArbitrary");4const test = () => {5    const shrunk = rawShrinkValue(nat(), 10);6    console.log(shrunk);7}8test();9Shrinkable {10  context: Context {11  },12  shrink: [Function (anonymous)]13}14const fc = require("fast-check");15const {nat} = require("fast-check/lib/check/arbitrary/NatArbitrary");16const test = () => {17    const shrunk = fc.shrink(nat(), 10);18    console.log(shrunk);19}20test();21Shrinkable {22  context: Context {23  },24  shrink: [Function (anonymous)]25}

Using AI Code Generation

1const fc = require('fast-check');2const {rawShrinkValue} = require('fast-check/lib/arbitrary/Shrinkable');3const {shrinkNumber} = require('fast-check/lib/arbitrary/number/NumberArbitrary');4const {shrinkString} = require('fast-check/lib/arbitrary/string/CharacterArbitrary');5const {shrinkObject} = require('fast-check/lib/arbitrary/object/ObjectArbitrary');6const shrinker = (value) => {7    if (typeof value === 'number') {8        return shrinkNumber(value);9    }10    if (typeof value === 'string') {11        return shrinkString(value);12    }13    if (typeof value === 'object') {14        return shrinkObject(value);15    }16    return [];17};18const value = {a: 1, b: 2};19const shrinkable = rawShrinkValue(value, shrinker);20shrinkable.shrink().forEach((v) => console.log(v.value));21I am using fast-check version 2.16.0. I am using the following code to import the rawShrinkValue method:22const {rawShrinkValue} = require('fast-check/lib/arbitrary/Shrinkable');23const rawShrinkValue = require('fast-check/lib/arbitrary/Shrinkable').rawShrinkValue;24const rawShrinkValue = require('fast-check/lib/arbitrary/Shrinkable').default.rawShrinkValue;25const rawShrinkValue = require('fast-check/lib/arbitrary/Shrinkable').rawShrinkValue.default;26None of these work. How can I import the rawShrinkValue method from the Shrinkable.js file?

Using AI Code Generation

1const fc = require('fast-check');2const { rawShrinkValue } = require('fast-check/lib/check/arbitrary/definition/Shrinkable.js');3const { isValid } = require('fast-check/lib/check/runner/RunnerParameters.js');4const { stringify } = require('fast-check/lib/utils/Json.js');5const { stringifyValue } = require('fast-check/lib/check/runner/Value.js');6const { stringifyValue_ } = require('fast-check/lib/check/runner/Value.js');7const { PathReporter } = require('io-ts/lib/PathReporter');8const { report } = require('io-ts/lib/PathReporter');9const { pipe } = require('fp-ts/lib/pipeable');10const { Either } = require('fp-ts/lib/Either');11const { map } = require('fp-ts/lib/Either');12const { identity } = require('fp-ts/lib/function');13const { fromEither } = require('fp-ts/lib/Either');14const { fromPredicate } = require('fp-ts/lib/Either');15const { fold } = require('fp-ts/lib/Either');16const { left } = require('fp-ts/lib/Either');17const { right } = require('fp-ts/lib/Either');18const { string } = require('io-ts/lib/Codec');19const { number } = require('io-ts/lib/Codec');20const { array } = require('io-ts/lib/Codec');21const { type } = require('io-ts/lib/Codec');22const { Codec } = require('io-ts/lib/Codec');23const { is } = require('io-ts/lib/Codec');24const { identity } = require('io-ts/lib/Codec');25const { literal } = require('io-ts/lib/Codec');26const { boolean } = require('io-ts/lib/Codec');27const { nullType } = require('io-ts/lib/Codec');28const { undefinedType } = require('io-ts/lib/Codec');29const { mixed } = require('io-ts/lib/Codec');30const { UnknownArray } = require('io-ts/lib/Codec');31const { UnknownRecord } = require('io-ts/lib/Codec');32const { UnknownC } = require('io-ts/lib/Codec');33const { union } = require('io-ts/lib/Codec');34const { intersection } = require('io-ts/lib/Codec');35const { sum } = require('io-ts/lib/Codec');

Using AI Code Generation

1const fc = require('fast-check');2const prop = (x) => x === 42;3const run = () => {4    const { counterexample } = fc.check(prop, { seed: 42 });5    console.log(counterexample);6    const shrinked = fc.rawShrinkValue(counterexample, prop);7    console.log(shrinked);8};9run();10const fc = require('fast-check');11const prop = (x) => x === 42;12const run = () => {13    const { counterexample } = fc.check(prop, { seed: 42 });14    console.log(counterexample);15    const shrinked = fc.rawShrinkValue(counterexample, prop);16    console.log(shrinked);17};18run();19const fc = require('fast-check');20const prop = (x) => x === 42;21const run = () => {22    const { counterexample } = fc.check(prop, { seed: 42 });23    console.log(counterexample);24    const shrinked = fc.rawShrinkValue(counterexample, prop);25    console.log(shrinked);26};27run();28const fc = require('fast-check');29const prop = (x) => x === 42;30const run = () => {31    const { counterexample } = fc.check(prop, { seed: 42 });32    console.log(counterexample);33    const shrinked = fc.rawShrinkValue(counterexample, prop);34    console.log(shrinked);35};36run();37const fc = require('fast-check');38const prop = (x) => x === 42;39const run = () => {40    const { counterexample } = fc.check(prop, { seed: 42 });

Automation Testing Tutorials

Learn to execute automation testing from scratch with LambdaTest Learning Hub. Right from setting up the prerequisites to run your first automation test, to following best practices and diving deeper into advanced test scenarios. LambdaTest Learning Hubs compile a list of step-by-step guides to help you be proficient with different test automation frameworks i.e. Selenium, Cypress, TestNG etc.