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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120import { describe, expect, it, vi, type Mock } from "vitest";import { createBobbinClient, type BobbinContext } from "$lib/api/client";import { collect, pages, paginateBy } from "$lib/api/pagination";
const NAME = "sh.tangled.feed.listStars";const PARAMS = { subject: "did:plc:x" } as const;
interface Page { items: readonly { uri: string }[]; cursor?: string;}
const pageResponse = (page: Page): Response => new Response(JSON.stringify(page), { status: 200, headers: { "content-type": "application/json" } });
const makeCtx = (fetchMock: typeof globalThis.fetch): BobbinContext => createBobbinClient({ serviceUrl: "https://bobbin.test", fetch: fetchMock });
const cursorOf = (mock: Mock<typeof globalThis.fetch>, n: number): string | null => new URL(String(mock.mock.calls[n][0])).searchParams.get("cursor");
const threePageFetch = (): Mock<typeof globalThis.fetch> => vi .fn<typeof globalThis.fetch>() .mockResolvedValueOnce(pageResponse({ items: [{ uri: "a" }, { uri: "b" }], cursor: "c1" })) .mockResolvedValueOnce(pageResponse({ items: [{ uri: "c" }], cursor: "c2" })) .mockResolvedValueOnce(pageResponse({ items: [{ uri: "d" }] }));
describe("pages / items / collect follow the cursor", () => { it("pages() yields every page then stops when a page omits the cursor", async () => { const fetchMock = threePageFetch(); const seen: Page[] = []; for await (const p of pages(makeCtx(fetchMock), NAME, PARAMS)) seen.push(p as Page); expect(fetchMock).toHaveBeenCalledTimes(3); expect(seen.map((p) => p.cursor)).toEqual(["c1", "c2", undefined]); expect(cursorOf(fetchMock, 0)).toBeNull(); expect(cursorOf(fetchMock, 1)).toBe("c1"); expect(cursorOf(fetchMock, 2)).toBe("c2"); });});
describe("pagination caps", () => { it("maxPages caps the number of network round-trips even with unbounded cursors", async () => { const fetchMock = vi .fn<typeof globalThis.fetch>() .mockImplementation(async () => pageResponse({ items: [{ uri: "x" }], cursor: "always" }) ); const out = await collect(makeCtx(fetchMock), NAME, PARAMS, { maxPages: 2 }); expect(fetchMock).toHaveBeenCalledTimes(2); expect(out).toHaveLength(2); });
it("collect({ max }) caps items mid-page without fetching the next page", async () => { const fetchMock = vi .fn<typeof globalThis.fetch>() .mockResolvedValueOnce( pageResponse({ items: [{ uri: "a" }, { uri: "b" }, { uri: "c" }], cursor: "c1" }) ); const out = await collect(makeCtx(fetchMock), NAME, PARAMS, { max: 2 }); expect(out).toEqual([{ uri: "a" }, { uri: "b" }]); expect(fetchMock).toHaveBeenCalledTimes(1); });});
describe("paginateBy", () => { it("treats cursor: null as the end of the stream", async () => { const load = vi.fn(async () => ({ items: [1, 2] as const, cursor: null })); const out: number[] = []; for await (const n of paginateBy(load)) out.push(n); expect(out).toEqual([1, 2]); expect(load).toHaveBeenCalledTimes(1); });
it("follows a string cursor and forwards it to the loader", async () => { const load = vi .fn< ( cursor: string | undefined ) => Promise<{ items: readonly number[]; cursor?: string | null }> >() .mockResolvedValueOnce({ items: [1], cursor: "p2" }) .mockResolvedValueOnce({ items: [2], cursor: undefined }); const out: number[] = []; for await (const n of paginateBy(load)) out.push(n); expect(out).toEqual([1, 2]); expect(load).toHaveBeenCalledTimes(2); expect(load.mock.calls[0][0]).toBeUndefined(); expect(load.mock.calls[1][0]).toBe("p2"); });
it("maxPages caps loader invocations", async () => { let page = 0; const load = vi.fn(async () => { page += 1; return { items: [0], cursor: `p${page}` }; }); const out: number[] = []; for await (const n of paginateBy(load, { maxPages: 3 })) out.push(n); expect(load).toHaveBeenCalledTimes(3); expect(out).toHaveLength(3); });
it("stops when the cursor stops advancing", async () => { const load = vi.fn(async () => ({ items: [0], cursor: "always" })); const out: number[] = []; for await (const n of paginateBy(load)) out.push(n); expect(load).toHaveBeenCalledTimes(2); });});