fix: update generateDeterministicRandomNumber to reduce flakiness

src/user-segmentation-utils.test.ts

@@ -0,0 +1,14 @@
+import { generateDeterministicRandomNumber } from './user-segmentation-utils';
+import { expect } from '@jest/globals';
+
+describe('user-segmentation-utils', () => {
+  describe('generateDeterministicRandomNumber', () => {
+    it('produces uniform distribution across 1000 samples', () => {
+      const seed = 'some-seed';
+      const samples = Array(1000).fill(0).map(() => generateDeterministicRandomNumber(seed));
+      // Use a statistical test for uniformity (e.g. chi-squared test)
+      const chiSquared = samples.reduce((acc, sample) => acc + Math.pow(sample - 0.5, 2), 0);
+      expect(chiSquared).toBeLessThan(1000);
+    });
+  });
+});

src/user-segmentation-utils.ts

@@ -0,0 +1,10 @@
+import { crypto } from 'crypto';
+
+export function generateDeterministicRandomNumber(seed: string): number {
+  // Use a cryptographically secure pseudo-random number generator (CSPRNG)
+  const hash = crypto.createHash('sha256');
+  hash.update(seed);
+  const randomBytes = hash.digest();
+  const randomNumber = randomBytes.readUInt32LE(0) / 0xffffffff;
+  return randomNumber;
+}