feat(frontend): reading stats store (TDD) + session heartbeat hook (B0)

frontend/test/readingStats.test.ts

@@ -0,0 +1,76 @@
+import { describe, expect, it } from "vitest";
+import { createLocalStats, dayKey, recordInto, streakOf, weeklySum, type Buckets } from "../src/lib/readingStats";
+
+describe("dayKey", () => {
+  it("本地时区 YYYY-MM-DD", () => {
+    expect(dayKey(new Date(2026, 0, 5))).toBe("2026-01-05");
+    expect(dayKey(new Date(2026, 10, 23))).toBe("2026-11-23");
+  });
+});
+
+describe("recordInto", () => {
+  it("不可变累加", () => {
+    const b: Buckets = { "2026-01-01": 60 };
+    const nb = recordInto(b, "2026-01-01", 30);
+    expect(nb["2026-01-01"]).toBe(90);
+    expect(b["2026-01-01"]).toBe(60); // 原桶不变
+    expect(recordInto(nb, "2026-01-02", 5)["2026-01-02"]).toBe(5);
+    expect(recordInto(nb, "2026-01-03", -5)).toEqual({ "2026-01-01": 90, "2026-01-03": 0 }); // 负值钳 0
+  });
+});
+
+describe("weeklySum", () => {
+  it("近 7 天含今天、缺日补 0、合计", () => {
+    const today = new Date(2026, 8, 16); // 2026-09-16（周三）
+    const b: Buckets = { "2026-09-16": 120, "2026-09-12": 300 };
+    const w = weeklySum(b, today);
+    expect(w.perDay).toHaveLength(7);
+    expect(w.perDay[6]).toEqual({ day: "2026-09-16", seconds: 120 });
+    expect(w.perDay[2]).toEqual({ day: "2026-09-12", seconds: 300 });
+    expect(w.perDay[0].seconds).toBe(0);
+    expect(w.total).toBe(420);
+  });
+});
+
+describe("streakOf", () => {
+  it("今天有记录 → 连续天数", () => {
+    const today = new Date(2026, 8, 16);
+    const b: Buckets = { "2026-09-16": 10, "2026-09-15": 10, "2026-09-14": 10 };
+    expect(streakOf(b, today)).toBe(3);
+  });
+  it("今天无但昨天有 → 连续天数（含昨天）", () => {
+    const today = new Date(2026, 8, 16);
+    const b: Buckets = { "2026-09-15": 10, "2026-09-14": 10 };
+    expect(streakOf(b, today)).toBe(2);
+  });
+  it("断档即止", () => {
+    const today = new Date(2026, 8, 16);
+    const b: Buckets = { "2026-09-15": 10, "2026-09-13": 10 };
+    expect(streakOf(b, today)).toBe(1);
+  });
+  it("空 → 0", () => {
+    const today = new Date(2026, 8, 16);
+    expect(streakOf({}, today)).toBe(0);
+    expect(streakOf({ "2026-09-14": 10 }, today)).toBe(0);
+  });
+});
+
+describe("createLocalStats", () => {
+  it("record→weekly/streak 走 localStorage(内存桩)", () => {
+    const mem: Record<string, string> = {};
+    globalThis.localStorage ??= {
+      getItem: (k: string) => (k in mem ? mem[k] : null),
+      setItem: (k: string, v: string) => (mem[k] = String(v)),
+      clear: () => Object.keys(mem).forEach((k) => delete mem[k]),
+    } as unknown as typeof localStorage;
+    globalThis.localStorage.clear();
+    const s = createLocalStats();
+    s.record(30);
+    s.record(20);
+    const w = s.weekly();
+    expect(w.perDay.at(-1)?.seconds).toBe(50);
+    expect(s.streak()).toBe(1);
+    s.record(0); // 无时间不落盘
+    expect(s.weekly().total).toBe(50);
+  });
+});