From 5e7c3ad7ed8c287b538de97d4de3a4df87e9a100 Mon Sep 17 00:00:00 2001 From: nsfisis Date: Sun, 8 Feb 2026 21:18:55 +0900 Subject: feat(study): use seeded PRNG for deterministic card shuffle order Shuffle order is now fixed within a study day by seeding mulberry32 with the study day boundary timestamp (3:00 AM rollover). Co-Authored-By: Claude Opus 4.6 --- src/client/utils/shuffle.test.ts | 54 ---------------------------------------- 1 file changed, 54 deletions(-) delete mode 100644 src/client/utils/shuffle.test.ts (limited to 'src/client/utils/shuffle.test.ts') diff --git a/src/client/utils/shuffle.test.ts b/src/client/utils/shuffle.test.ts deleted file mode 100644 index 687aec4..0000000 --- a/src/client/utils/shuffle.test.ts +++ /dev/null @@ -1,54 +0,0 @@ -import { describe, expect, it } from "vitest"; -import { shuffle } from "./shuffle"; - -describe("shuffle", () => { - it("returns an array of the same length", () => { - const input = [1, 2, 3, 4, 5]; - const result = shuffle(input); - expect(result).toHaveLength(input.length); - }); - - it("contains all original elements", () => { - const input = [1, 2, 3, 4, 5]; - const result = shuffle(input); - expect(result.sort()).toEqual(input.sort()); - }); - - it("does not mutate the original array", () => { - const input = [1, 2, 3, 4, 5]; - const original = [...input]; - shuffle(input); - expect(input).toEqual(original); - }); - - it("returns empty array for empty input", () => { - expect(shuffle([])).toEqual([]); - }); - - it("returns single element array unchanged", () => { - expect(shuffle([1])).toEqual([1]); - }); - - it("works with objects", () => { - const input = [{ id: 1 }, { id: 2 }, { id: 3 }]; - const result = shuffle(input); - expect(result).toHaveLength(3); - expect(result.map((x) => x.id).sort()).toEqual([1, 2, 3]); - }); - - it("actually shuffles (statistical test)", () => { - const input = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; - let sameOrderCount = 0; - const iterations = 100; - - for (let i = 0; i < iterations; i++) { - const result = shuffle(input); - if (JSON.stringify(result) === JSON.stringify(input)) { - sameOrderCount++; - } - } - - // Should very rarely keep original order (probability ~1/3628800) - expect(sameOrderCount).toBeLessThan(iterations * 0.1); - }); -}); -- cgit v1.3-1-g0d28