🐛 Jump PRNG in infiniteStream loop after first iteration

packages/fast-check/src/arbitrary/_internals/StreamArbitrary.ts

@@ -36,6 +36,7 @@ export class StreamArbitrary<T> extends Arbitrary<Stream<T>> {
             safePush(seenValues, value);
           }
           yield value;
+          clonedMrng.jump();
         }
       };
       const s = new Stream(g(this.arb, mrng.clone()));

packages/fast-check/src/random/generator/Random.ts

@@ -1,5 +1,5 @@
 import type { RandomGenerator } from 'pure-rand';
-import { unsafeUniformBigIntDistribution, unsafeUniformIntDistribution } from 'pure-rand';
+import { unsafeUniformBigIntDistribution, unsafeUniformIntDistribution, unsafeSkipN } from 'pure-rand';
 
 /**
  * Wrapper around an instance of a `pure-rand`'s random number generator
@@ -31,6 +31,18 @@ export class Random {
     return new Random(this.internalRng);
   }
 
+  /**
+   * Jump the random number generator by a fixed amount
+   * @internal
+   */
+  jump(): void {
+    if ('unsafeJump' in this.internalRng && typeof this.internalRng.unsafeJump === 'function') {
+      this.internalRng.unsafeJump();
+    } else {
+      unsafeSkipN(this.internalRng, 42);
+    }
+  }
+
   /**
    * Generate an integer having `bits` random bits
    * @param bits - Number of bits to generate

packages/fast-check/test/e2e/__snapshots__/NoRegression.spec.ts.snap

@@ -657,11 +657,11 @@ Execution summary:
 exports[`NoRegression (async) > infiniteStream (to Promise) 1`] = `
 [Error: Property failed after 1 tests
 { seed: 42, path: "0", endOnFailure: true }
-Counterexample: [Stream(Promise.resolve(-2),Promise.resolve(-22),Promise.resolve(24),Promise.resolve(8),Promise.resolve(9975393),Promise.resolve(25),Promise.resolve(-757343395),Promise.resolve(-1407968202),Promise.resolve(6),Promise.resolve(2147483645)…)]
+Counterexample: [Stream(Promise.resolve(-2),Promise.resolve(-1285903064),Promise.resolve(2103360753),Promise.resolve(-13),Promise.resolve(9),Promise.resolve(7),Promise.resolve(3),Promise.resolve(-15),Promise.resolve(-10),Promise.resolve(2147483646)…)]
 Shrunk 0 time(s)
 
 Execution summary:
-× [Stream(Promise.resolve(-2),Promise.resolve(-22),Promise.resolve(24),Promise.resolve(8),Promise.resolve(9975393),Promise.resolve(25),Promise.resolve(-757343395),Promise.resolve(-1407968202),Promise.resolve(6),Promise.resolve(2147483645)…)]]
+× [Stream(Promise.resolve(-2),Promise.resolve(-1285903064),Promise.resolve(2103360753),Promise.resolve(-13),Promise.resolve(9),Promise.resolve(7),Promise.resolve(3),Promise.resolve(-15),Promise.resolve(-10),Promise.resolve(2147483646)…)]]
 `;
 
 exports[`NoRegression (async) > number 1`] = `
@@ -3257,11 +3257,11 @@ Execution summary:
 exports[`NoRegression > infiniteStream 1`] = `
 [Error: Property failed after 1 tests
 { seed: 42, path: "0", endOnFailure: true }
-Counterexample: [Stream(2147483646,9,24,8,9975393,2147483642,1390140253,739515446,6,28…)]
+Counterexample: [Stream(2147483646,861580584,2103360753,2147483635,2147483626,7,3,16,2147483638,29…)]
 Shrunk 0 time(s)
 
 Execution summary:
-× [Stream(2147483646,9,24,8,9975393,2147483642,1390140253,739515446,6,28…)]]
+× [Stream(2147483646,861580584,2103360753,2147483635,2147483626,7,3,16,2147483638,29…)]]
 `;
 
 exports[`NoRegression > int8Array 1`] = `

packages/fast-check/test/unit/arbitrary/__test-helpers__/RandomHelpers.ts

@@ -10,17 +10,19 @@ export function fakeRandom(): { instance: Random } & Omit<MaybeMocked<Random>, '
   const nextBigInt = vi.fn();
   const nextDouble = vi.fn();
   const getState = vi.fn();
+  const jump = vi.fn();
   class MyRandom extends Random {
     clone = clone;
     next = next;
     nextBoolean = nextBoolean;
     nextInt = nextInt;
     nextBigInt = nextBigInt;
     getState = getState;
+    jump = jump;
   }
 
   // Calling `new MyRandom` triggers a call to the default ctor of `Random`.
   // As we don't use anything from this base class, we just pass the ctor with a value that looks ok for it.
   const instance = new MyRandom({ clone: () => null } as any);
-  return { instance, clone, next, nextBoolean, nextInt, nextBigInt, nextDouble, getState };
+  return { instance, clone, next, nextBoolean, nextInt, nextBigInt, nextDouble, getState, jump };
 }