사소한 리팩토링

test/unit/filesystem-cache.test.ts

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+import { describe, expect, it, vi } from "vitest";
+import { FilesystemCache } from "#lib/features/filesystem/cache.svelte.ts";
+
+interface Entry {
+  id: number;
+  name: string;
+}
+
+const createCache = (options?: {
+  local?: Record<number, string>;
+  server?: Record<number, string>;
+}) => {
+  const local = options?.local ?? {};
+  const server = options?.server ?? {};
+  const fetchFromServer = vi.fn(async (id: number): Promise<Entry> => {
+    if (!(id in server)) throw new Error("Not found");
+    return { id, name: server[id]! };
+  });
+  const cache = new FilesystemCache<number, Entry>({
+    fetchFromIndexedDB: async (id) => (id in local ? { id, name: local[id]! } : undefined),
+    fetchFromServer,
+    bulkFetchFromIndexedDB: async (ids) =>
+      new Map([...ids].filter((id) => id in local).map((id) => [id, { id, name: local[id]! }])),
+    bulkFetchFromServer: async (ids) =>
+      new Map([...ids.keys()].map((id) => [id, { id, name: server[id]! }])),
+  });
+  return { cache, server, fetchFromServer };
+};
+
+const flush = () => new Promise((resolve) => setTimeout(resolve, 0));
+
+describe("FilesystemCache", () => {
+  it("revalidates again after invalidation during a pending request, coalescing repeated calls", async () => {
+    const pending = Promise.withResolvers<Entry>();
+    const fetchFromServer = vi
+      .fn<(id: number) => Promise<Entry>>()
+      .mockImplementationOnce(() => pending.promise)
+      .mockResolvedValue({ id: 1, name: "new" });
+    const cache = new FilesystemCache<number, Entry>({
+      fetchFromIndexedDB: async () => undefined,
+      fetchFromServer,
+    });
+    const loading = cache.get(1);
+    await vi.waitFor(() => expect(fetchFromServer).toHaveBeenCalledTimes(1));
+
+    cache.invalidate(1);
+    cache.invalidate(1);
+    cache.invalidate(1);
+    pending.resolve({ id: 1, name: "old" });
+    const entry = await loading;
+    await vi.waitFor(() => expect(entry.name).toBe("new"));
+    expect(fetchFromServer).toHaveBeenCalledTimes(2);
+  });
+
+  it("revalidates only invalidated entries after a pending bulk request", async () => {
+    const pending = Promise.withResolvers<Map<number, Entry>>();
+    const fetchFromServer = vi.fn(async (id: number) => ({ id, name: "new" }));
+    const bulkFetchFromServer = vi.fn(() => pending.promise);
+    const cache = new FilesystemCache<number, Entry>({
+      fetchFromIndexedDB: async () => undefined,
+      fetchFromServer,
+      bulkFetchFromIndexedDB: async () => new Map(),
+      bulkFetchFromServer,
+    });
+    const loading = cache.bulkGet(new Set([1, 2]));
+    await vi.waitFor(() => expect(bulkFetchFromServer).toHaveBeenCalledTimes(1));
+    cache.invalidate(1);
+    pending.resolve(new Map([1, 2].map((id) => [id, { id, name: "old" }])));
+
+    const entries = await loading;
+    await vi.waitFor(() => expect(entries.get(1)?.name).toBe("new"));
+    expect(entries.get(2)?.name).toBe("old");
+    expect(fetchFromServer).toHaveBeenCalledTimes(1);
+  });
+
+  it("preserves invalidation when a pending request fails", async () => {
+    vi.spyOn(console, "error").mockImplementation(() => {});
+    const pending = Promise.withResolvers<Entry>();
+    const fetchFromServer = vi
+      .fn<() => Promise<Entry>>()
+      .mockImplementationOnce(() => pending.promise)
+      .mockResolvedValue({ id: 1, name: "new" });
+    const cache = new FilesystemCache<number, Entry>({
+      fetchFromIndexedDB: async () => ({ id: 1, name: "local" }),
+      fetchFromServer,
+    });
+    const entry = await cache.get(1);
+    await vi.waitFor(() => expect(fetchFromServer).toHaveBeenCalledTimes(1));
+    cache.invalidate(1);
+    pending.reject(new Error("Failed"));
+
+    await vi.waitFor(() => expect(entry.name).toBe("new"));
+    expect(fetchFromServer).toHaveBeenCalledTimes(2);
+  });
+
+  it("doesn't revalidate evicted entries after a pending bulk request", async () => {
+    const pending = Promise.withResolvers<Map<number, Entry>>();
+    const fetchFromServer = vi.fn(async (id: number) => ({ id, name: "new" }));
+    const bulkFetchFromServer = vi.fn(() => pending.promise);
+    const cache = new FilesystemCache<number, Entry>({
+      fetchFromIndexedDB: async () => undefined,
+      fetchFromServer,
+      bulkFetchFromIndexedDB: async () => new Map(),
+      bulkFetchFromServer,
+    });
+    const loading = cache.bulkGet(new Set([1]));
+    await vi.waitFor(() => expect(bulkFetchFromServer).toHaveBeenCalledTimes(1));
+    cache.invalidate(1);
+    cache.evict(1);
+    const replacement = await cache.get(1);
+    pending.resolve(new Map([[1, { id: 1, name: "old" }]]));
+    await loading;
+    await flush();
+
+    expect(replacement.name).toBe("new");
+    expect(fetchFromServer).toHaveBeenCalledTimes(1);
+  });
+
+  it("resolves with the local value first and updates it in place", async () => {
+    const { cache } = createCache({ local: { 1: "local" }, server: { 1: "server" } });
+
+    const entry = await cache.get(1);
+    expect(entry.name).toBe("local");
+
+    await flush();
+    expect(entry.name).toBe("server");
+  });
+
+  it("returns the cached value synchronously", async () => {
+    const { cache } = createCache({ server: { 1: "server" } });
+
+    const entry = await cache.get(1);
+    await flush();
+
+    expect(cache.get(1)).toBe(entry);
+  });
+
+  it("revalidates entries when invalidated", async () => {
+    const { cache, server, fetchFromServer } = createCache({ server: { 1: "old" } });
+    const entry = await cache.get(1);
+    await flush();
+
+    server[1] = "new";
+    cache.invalidate(1);
+    await flush();
+
+    expect(fetchFromServer).toHaveBeenCalledTimes(2);
+    expect(entry.name).toBe("new");
+  });
+
+  it("ignores invalidation of entries that haven't been loaded", () => {
+    const { cache, fetchFromServer } = createCache();
+
+    cache.invalidate(1);
+
+    expect(fetchFromServer).not.toHaveBeenCalled();
+  });
+
+  it("rejects if loading fails without a cached value", async () => {
+    const { cache } = createCache();
+    vi.spyOn(console, "error").mockImplementation(() => {});
+
+    await expect(cache.get(1)).rejects.toThrow("Not found");
+    // Can be retried
+    await expect(cache.get(1)).rejects.toThrow("Not found");
+  });
+
+  it("loads multiple entries at once", async () => {
+    const { cache } = createCache({ local: { 1: "local" }, server: { 1: "a", 2: "b" } });
+
+    const entries = await cache.bulkGet(new Set([1, 2]));
+    await flush();
+
+    expect(entries.get(1)?.name).toBe("a");
+    expect(entries.get(2)?.name).toBe("b");
+    expect(cache.get(2)).toBe(entries.get(2));
+  });
+});