feat: add telegram-style resource stream

src/components/messageStream/hooks/useGroupedByDay.test.ts

@@ -0,0 +1,53 @@
+import { describe, expect, it } from "vitest";
+import { renderHook } from "@testing-library/react";
+import { useGroupedByDay } from "./useGroupedByDay";
+import type { Post } from "../../../types/post";
+
+function makePost(id: string, isoDate: string): Post {
+  return {
+    id,
+    categoryId: 1,
+    categorySlug: "x",
+    language: "zh-CN",
+    attachments: [],
+    isRecommended: false,
+    publishedAt: isoDate,
+    updatedAt: isoDate,
+    text: id,
+  };
+}
+
+describe("useGroupedByDay", () => {
+  it("groups posts by local date", () => {
+    const posts: Post[] = [
+      makePost("a", "2026-02-27T10:00:00.000Z"),
+      makePost("b", "2026-02-27T23:00:00.000Z"),
+      makePost("c", "2026-02-28T01:00:00.000Z"),
+      makePost("d", "2026-05-16T12:00:00.000Z"),
+    ];
+    const { result } = renderHook(() => useGroupedByDay(posts, "zh-CN"));
+    expect(result.current.length).toBeGreaterThanOrEqual(2);
+    const allIds = result.current.flatMap((g) => g.items.map((p) => p.id));
+    expect(allIds).toEqual(["a", "b", "c", "d"]);
+  });
+
+  it("preserves input order within groups", () => {
+    const posts: Post[] = [
+      makePost("first", "2026-03-01T10:00:00.000Z"),
+      makePost("second", "2026-03-01T11:00:00.000Z"),
+      makePost("third", "2026-03-01T12:00:00.000Z"),
+    ];
+    const { result } = renderHook(() => useGroupedByDay(posts, "en"));
+    expect(result.current).toHaveLength(1);
+    expect(result.current[0].items.map((p) => p.id)).toEqual([
+      "first",
+      "second",
+      "third",
+    ]);
+  });
+
+  it("returns empty array for empty input", () => {
+    const { result } = renderHook(() => useGroupedByDay([], "zh-CN"));
+    expect(result.current).toEqual([]);
+  });
+});