✨ Add option to generate unicode values in object (#5010)

**Description**

Recent bugs found in Vitest around badly formed snapshot names would
have benefit from having a built-in way to switch on unicode generation
on `object` and `anything`.

The proposed PR adds a new flag onto them. It allows users to force
generation of unicode strings as keys and values of the instances
produced by these two helpers. The flag is called `withUnicodeString`.

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**Advanced**

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- [x] Category: ✨ Introduce new features
- [x] Impacts: N.A.

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.yarn/versions/62e8ed33.yml

@@ -0,0 +1,8 @@
+releases:
+  fast-check: minor
+
+declined:
+  - "@fast-check/ava"
+  - "@fast-check/jest"
+  - "@fast-check/vitest"
+  - "@fast-check/worker"

packages/fast-check/src/arbitrary/_internals/helpers/QualifiedObjectConstraints.ts

@@ -2,6 +2,7 @@ import type { Arbitrary } from '../../../check/arbitrary/definition/Arbitrary';
 import { boolean } from '../../boolean';
 import { constant } from '../../constant';
 import { double } from '../../double';
+import { fullUnicodeString } from '../../fullUnicodeString';
 import { maxSafeInteger } from '../../maxSafeInteger';
 import { oneof } from '../../oneof';
 import { string } from '../../string';
@@ -103,6 +104,13 @@ export interface ObjectConstraints {
    * @remarks Since 2.13.0
    */
   withSparseArray?: boolean;
+  /**
+   * Replace the arbitrary of strings defaulted for key and values by one able to generate unicode strings with non-ascii characters.
+   * If you override key and/or values constraint, this flag will not apply to your override.
+   * @defaultValue false
+   * @remarks Since 3.19.0
+   */
+  withUnicodeString?: boolean;
 }
 
 /** @internal */
@@ -113,18 +121,24 @@ type ObjectConstraintsOptionalValues = 'depthSize' | 'maxDepth' | 'maxKeys' | 's
  * @internal
  */
 export type QualifiedObjectConstraints = Required<
-  Omit<ObjectConstraints, 'withBoxedValues' | ObjectConstraintsOptionalValues>
+  Omit<ObjectConstraints, 'withBoxedValues' | 'withUnicodeString' | ObjectConstraintsOptionalValues>
 > &
   Pick<ObjectConstraints, ObjectConstraintsOptionalValues>;
 
 /** @internal */
-function defaultValues(constraints: { size: SizeForArbitrary }): Arbitrary<unknown>[] {
+type DefaultValuesConstraints = { size: SizeForArbitrary };
+
+/** @internal */
+function defaultValues(
+  constraints: DefaultValuesConstraints,
+  stringArbitrary: (constraints: DefaultValuesConstraints) => Arbitrary<string>,
+): Arbitrary<unknown>[] {
   return [
     boolean(),
     maxSafeInteger(),
     double(),
-    string(constraints),
-    oneof(string(constraints), constant(null), constant(undefined)),
+    stringArbitrary(constraints),
+    oneof(stringArbitrary(constraints), constant(null), constant(undefined)),
   ];
 }
 
@@ -146,11 +160,12 @@ export function toQualifiedObjectConstraints(settings: ObjectConstraints = {}):
   function orDefault<T>(optionalValue: T | undefined, defaultValue: T): T {
     return optionalValue !== undefined ? optionalValue : defaultValue;
   }
+  const stringArbitrary = settings.withUnicodeString ? fullUnicodeString : string;
   const valueConstraints = { size: settings.size };
   return {
-    key: orDefault(settings.key, string(valueConstraints)),
+    key: orDefault(settings.key, stringArbitrary(valueConstraints)),
     values: boxArbitrariesIfNeeded(
-      orDefault(settings.values, defaultValues(valueConstraints)),
+      orDefault(settings.values, defaultValues(valueConstraints, stringArbitrary)),
       orDefault(settings.withBoxedValues, false),
     ),
     depthSize: settings.depthSize,

packages/fast-check/test/e2e/GenerateAllValues.spec.ts

@@ -75,6 +75,7 @@ describe(`Generate all values (seed: ${seed})`, () => {
           withDate: true,
           withTypedArray: true,
           withSparseArray: true,
+          withUnicodeString: true,
           ...(typeof BigInt !== 'undefined' ? { withBigInt: true } : {}),
         });
         while (++numTries <= 10000) {

packages/fast-check/test/unit/arbitrary/_internals/builders/AnyArbitraryBuilder.spec.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import fc from 'fast-check';
+import fc, { stringify } from 'fast-check';
 
 import { anyArbitraryBuilder } from '../../../../../src/arbitrary/_internals/builders/AnyArbitraryBuilder';
 import type { ObjectConstraints } from '../../../../../src/arbitrary/_internals/helpers/QualifiedObjectConstraints';
@@ -102,6 +102,7 @@ describe('anyArbitraryBuilder (integration)', () => {
         withSet: fc.boolean(),
         withSparseArray: fc.boolean(),
         withTypedArray: fc.boolean(),
+        withUnicodeString: fc.boolean(),
       },
       { requiredKeys: [] },
     )
@@ -148,6 +149,9 @@ describe('anyArbitraryBuilder (integration)', () => {
     if (!extra.withTypedArray) {
       expect(isTypedArray(v)).toBe(false);
     }
+    if (!extra.withUnicodeString) {
+      expect(stringify(v)).toSatisfy(doesNotIncludeAnySurrogateCharacter);
+    }
     // No check for !extra.withObjectString as nothing prevent normal string builders to build such strings
     // In the coming major releases withObjectString might even disappear
   };
@@ -174,6 +178,11 @@ describe('anyArbitraryBuilder (integration)', () => {
 
 // Helpers
 
+function doesNotIncludeAnySurrogateCharacter(s: string): boolean {
+  // No character is a part of a surrogate pair
+  return s.split('').every((c) => c < '\uD800' || c > '\uDFFF');
+}
+
 function isBigInt(v: unknown): boolean {
   return typeof v === 'bigint';
 }

packages/fast-check/test/unit/utils/stringify.spec.ts

@@ -37,7 +37,7 @@ class CustomTagThrowingToString {
   }
 }
 
-const anythingEnableAll = {
+const anythingEnableAll: fc.ObjectConstraints = {
   withBoxedValues: true,
   withMap: true,
   withSet: true,
@@ -46,6 +46,7 @@ const anythingEnableAll = {
   withDate: true,
   withTypedArray: true,
   withSparseArray: true,
+  withUnicodeString: true,
   ...(typeof BigInt !== 'undefined' ? { withBigInt: true } : {}),
 };