Test quak backup end to end against a fake Ente server (closes #186)

test/cli/backup-end-to-end.test.ts runs backupCommand through run, as
bin/quak.ts does, with the real loadSession reading a session saved after
logging in, and every request answered by a fake of the Ente HTTP API serving
data encrypted with libsodium. It covers the backup tree of an account with
two albums of its own and one shared with it, a second run that downloads
nothing, a download that succeeds after two 503s, a 404 recorded in
failures.json with exit 1, a refresh answered 401 with exit 3, and --verify
putting back an original changed on disk.

The fake server and the account it logs in moved from the backup-metadata
test into test/ente-server.ts, unchanged, so both tests use them.

Model: opus-5-5

README.md

@@ -843,7 +843,8 @@ The library's primary surface is the cache-backed `Library`; the lower-level
 `Client` sits underneath it and is covered by the Design sections above. The
 test suite is the canonical, executable documentation — `test/library/` and
 `test/client/usage.test.ts` walk most operations, `test/cli/backup.test.ts`
-walks `lib.backup()`, and `yarn test` verifies them.
+walks `lib.backup()`, `test/cli/backup-end-to-end.test.ts` runs `quak backup`
+against a fake of the Ente HTTP API, and `yarn test` verifies them.
 
 ### Opening a library
 

TODO.md

@@ -25,6 +25,17 @@ declares one.
 
 # Completed Steps
 
+- 2026-10-14: `test/cli/backup-end-to-end.test.ts` runs `quak backup` as cron
+  does (issue 186): `backupCommand` and `run`, the real `loadSession` reading a
+  session saved after logging in, and every request answered by a fake of the
+  Ente HTTP API serving data encrypted with libsodium. It covers the backup tree
+  of an account with two albums of its own and one shared with it, a second run
+  that downloads nothing, a download that succeeds after two 503s, a 404 that
+  lands in `failures.json` with exit 1, a refresh answered 401 with exit 3, and
+  `--verify` putting back an original changed on disk. The fake server and the
+  account it logs in moved from the backup-metadata test into
+  `test/ente-server.ts`, unchanged.
+
 - 2026-10-06: The README says how to run `quak backup` from cron (issue 170):
   log in once as the job's user, a crontab with a backup every night and
   `--verify` on Sundays appending to a log file, and the `HOME` and

test/cli/backup-end-to-end.test.ts

@@ -0,0 +1,635 @@
+/**
+ * `quak backup`, end to end.
+ *
+ * Each test runs the command as cron runs it: `backupCommand` reads the
+ * session file that logging in saved, opens the library on the real `Client`
+ * and backs the whole account up into a directory, and `run` turns the outcome
+ * into the exit code, as `bin/quak.ts` does. Only the server is a stand-in:
+ * `buildMetaFetch` from `test/ente-server.ts` answers the Ente HTTP API from
+ * data this file encrypts with libsodium, as Ente's clients encrypt it. So
+ * quak's own code fetches each original, decrypts it, checks it against the
+ * hash its uploader recorded and unpacks a live photo, and quak's own retries
+ * repeat a failed request.
+ *
+ * The account, user 42, has three albums:
+ *
+ *     Trips              its own: beach.jpg
+ *     Family             its own: beach.jpg and the live photo IMG_0002.HEIC
+ *     Friend's Wedding   shared with it by user 99: toast.mp4
+ *
+ * beach.jpg is one file in two albums. It holds EXIF (a Canon EOS R5), and
+ * Ente has ML data for it. All three files were taken at noon on 1 March 2024.
+ */
+
+import {
+    existsSync,
+    lstatSync,
+    mkdtempSync,
+    readdirSync,
+    readFileSync,
+    readlinkSync,
+    rmSync,
+    writeFileSync,
+} from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { Writable } from "node:stream";
+import { gzipSync } from "node:zlib";
+import sodium from "libsodium-wrappers-sumo";
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+
+import {
+    backupCommand,
+    saveSession,
+    type CliContext,
+} from "../../src/cli-commands.js";
+import { run } from "../../src/cli-run.js";
+import { loadSession } from "../../src/cli-session.js";
+import { Client } from "../../src/client.js";
+import { init, toBase64 } from "../../src/crypto/index.js";
+import { UNATTENDED_RETRY_OPTIONS } from "../../src/retry.js";
+import {
+    buildAccount,
+    buildMetaFetch,
+    encryptSecretbox,
+    encryptStreamBlob,
+} from "../ente-server.js";
+import { HEIC_WITH_EXIF } from "../exif-heic.js";
+import { JPEG_WITH_EXIF } from "../exif-jpeg.js";
+import { blake2b, livePhotoHash, livePhotoZip, VIDEO } from "../live-photo.js";
+
+const EMAIL = "backup@example.com";
+const PASSWORD = "backup-password";
+// The fake server logs every account in as user 42.
+const USER_ID = 42;
+const FRIEND_ID = 99;
+
+// Noon on 1 March 2024 in the time zone of the machine running the test, the
+// one quak dates save paths in, in microseconds, as Ente records times.
+const TAKEN = new Date(2024, 2, 1, 12).getTime() * 1000;
+// The date folder every original is saved in.
+const DAY = "2024/2024-03/2024-03-01";
+
+const TOAST = new TextEncoder().encode("a few seconds of the wedding toast");
+
+// Ente's ML data for beach.jpg: a face it found, and the photo's CLIP
+// embedding.
+const ML_DATA = {
+    face: { faces: [{ faceID: "100_1", score: 0.98 }] },
+    clip: { embedding: [0.5, 0.6, 0.7] },
+};
+
+// Each file's ID, its owner, its original as uploaded, and the metadata its
+// uploader recorded. `fileType` is Ente's number for the kind: 0 an image, 1 a
+// video, 2 a live photo, whose original is a ZIP of its image and its video.
+// `hash` is the content hash a download must match.
+const BEACH = {
+    id: 100,
+    ownerID: USER_ID,
+    original: JPEG_WITH_EXIF,
+    metadata: {
+        title: "beach.jpg",
+        fileType: 0,
+        hash: blake2b(JPEG_WITH_EXIF),
+    },
+};
+const TOAST_VIDEO = {
+    id: 200,
+    ownerID: FRIEND_ID,
+    original: TOAST,
+    metadata: { title: "toast.mp4", fileType: 1, hash: blake2b(TOAST) },
+};
+const LIVE_PHOTO = {
+    id: 300,
+    ownerID: USER_ID,
+    original: livePhotoZip({
+        "image.heic": HEIC_WITH_EXIF,
+        "video.mov": VIDEO,
+    }),
+    metadata: {
+        title: "IMG_0002.HEIC",
+        fileType: 2,
+        hash: livePhotoHash(HEIC_WITH_EXIF, VIDEO),
+    },
+};
+
+// The fake Ente server, as the `fetch` quak sends its requests through.
+let server: typeof globalThis.fetch;
+let root: string;
+let sessionDir: string;
+
+// The fake server, holding the account encrypted as Ente's clients upload it.
+const buildServer = async () => {
+    const account = await buildAccount(PASSWORD);
+
+    // An album as `/collections/v2` lists it, its name encrypted with its own
+    // key. An album of the account's own carries that key encrypted with the
+    // master key; an album shared with it carries the key sealed to its public
+    // key, and no nonce.
+    const album = (id: number, name: string, ownerID: number) => {
+        const key = sodium.crypto_secretbox_keygen();
+        const encryptedName = encryptSecretbox(
+            new TextEncoder().encode(name),
+            key,
+        );
+        let keyFields: { encryptedKey: string; keyDecryptionNonce?: string };
+        if (ownerID === USER_ID) {
+            const encryptedKey = encryptSecretbox(key, account.masterKey);
+            keyFields = {
+                encryptedKey: toBase64(encryptedKey.ciphertext),
+                keyDecryptionNonce: toBase64(encryptedKey.nonce),
+            };
+        } else {
+            const sealedKey = sodium.crypto_box_seal(key, account.publicKey);
+            keyFields = { encryptedKey: toBase64(sealedKey) };
+        }
+        const row = {
+            id,
+            owner: { id: ownerID },
+            ...keyFields,
+            encryptedName: toBase64(encryptedName.ciphertext),
+            nameDecryptionNonce: toBase64(encryptedName.nonce),
+            type: "album",
+            updationTime: TAKEN,
+        };
+        return { key, row };
+    };
+    const trips = album(10, "Trips", USER_ID);
+    const family = album(20, "Family", USER_ID);
+    const wedding = album(30, "Friend's Wedding", FRIEND_ID);
+
+    // Each file's original is encrypted with the file's own key, as one
+    // secretstream, which the server serves whole.
+    const encrypted = (file: typeof BEACH) => {
+        const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
+        return { file, key, content: encryptStreamBlob(file.original, key) };
+    };
+    const beach = encrypted(BEACH);
+    const toast = encrypted(TOAST_VIDEO);
+    const livePhoto = encrypted(LIVE_PHOTO);
+
+    // A file as an album's `/collections/v2/diff` lists it: its key encrypted
+    // with the album's key, its metadata encrypted with its own key, and the
+    // header that starts the decryption of its original.
+    const inAlbum = (
+        { file, key, content }: ReturnType<typeof encrypted>,
+        collectionID: number,
+        albumKey: Uint8Array,
+    ) => {
+        const encryptedKey = encryptSecretbox(key, albumKey);
+        const metadata = encryptStreamBlob(
+            new TextEncoder().encode(
+                JSON.stringify({
+                    ...file.metadata,
+                    creationTime: TAKEN,
+                    modificationTime: TAKEN,
+                }),
+            ),
+            key,
+        );
+        return {
+            id: file.id,
+            collectionID,
+            ownerID: file.ownerID,
+            encryptedKey: toBase64(encryptedKey.ciphertext),
+            keyDecryptionNonce: toBase64(encryptedKey.nonce),
+            metadata: {
+                encryptedData: toBase64(metadata.ciphertext),
+                decryptionHeader: toBase64(metadata.header),
+            },
+            file: { decryptionHeader: toBase64(content.header) },
+            thumbnail: {
+                decryptionHeader: toBase64(sodium.randombytes_buf(24)),
+            },
+            updationTime: TAKEN,
+        };
+    };
+
+    // ML data is gzipped JSON, encrypted with the file's key.
+    const mlData = encryptStreamBlob(
+        gzipSync(JSON.stringify(ML_DATA)),
+        beach.key,
+    );
+
+    return buildMetaFetch({
+        verifier: account.verifier,
+        srpAttributes: account.srpAttributes,
+        keyAttributes: account.keyAttributes,
+        encryptedToken: account.encryptedToken,
+        collections: [trips.row, family.row, wedding.row],
+        filesByCollection: {
+            10: [inAlbum(beach, 10, trips.key)],
+            20: [
+                inAlbum(beach, 20, family.key),
+                inAlbum(livePhoto, 20, family.key),
+            ],
+            30: [inAlbum(toast, 30, wedding.key)],
+        },
+        encryptedMLData: {
+            100: {
+                encryptedData: toBase64(mlData.ciphertext),
+                decryptionHeader: toBase64(mlData.header),
+            },
+        },
+        fileCiphertexts: {
+            100: beach.content.ciphertext,
+            200: toast.content.ciphertext,
+            300: livePhoto.content.ciphertext,
+        },
+    });
+};
+
+beforeAll(async () => {
+    await init();
+    await sodium.ready;
+    root = mkdtempSync(join(tmpdir(), "quak-backup-end-to-end-"));
+    server = await buildServer();
+
+    // Log in once, as `quak login` does: the session file it saves is what
+    // every backup below reads.
+    sessionDir = join(root, "session");
+    const client = await Client.login({
+        email: EMAIL,
+        password: PASSWORD,
+        apiOptions: { fetch: server },
+    });
+    saveSession(sessionDir, client.toJSON());
+});
+
+afterAll(() => {
+    rmSync(root, { recursive: true, force: true });
+});
+
+// Run `quak backup <dir>` as `bin/quak.ts` runs it, sending its requests
+// through `fetch`, and return its exit code and everything it printed on
+// stderr. Its requests are retried as those of `quak backup` are, except that
+// a retry does not wait. Its cache is beside `dir`, so each run of one
+// directory finds the cache the run before it left, as cron's runs find the
+// user's.
+const backup = async (
+    dir: string,
+    opts: { verify?: boolean } = {},
+    fetch = server,
+): Promise<{ code: number; stderr: string }> => {
+    let printed = "";
+    const stderr = new Writable({
+        write(chunk: Buffer, _encoding, done) {
+            printed += chunk.toString();
+            done();
+        },
+    });
+    const stdout = new Writable({
+        write(_chunk, _encoding, done) {
+            done();
+        },
+    });
+    // A backup never prompts: any of these ends the run with exit 1.
+    const prompted = async (): Promise<never> => {
+        throw new Error("quak backup prompted");
+    };
+    const ctx: CliContext = {
+        stdout,
+        stderr,
+        sessionDir,
+        cacheDir: `${dir}-cache`,
+        loadSession: (path) =>
+            loadSession(path, {
+                fetch,
+                retry: { ...UNATTENDED_RETRY_OPTIONS, sleep: async () => {} },
+            }),
+        login: prompted,
+        prompt: prompted,
+        promptSecret: prompted,
+    };
+    const code = await new Promise<number>((resolve) => {
+        void run(backupCommand(ctx, dir, opts), stdout, stderr, resolve);
+    });
+    return { code, stderr: printed };
+};
+
+// The ID of the file whose original a request downloads, or undefined for any
+// other request. quak downloads an original from
+// `https://files.ente.io/?fileID=<id>`.
+const downloadOf = (input: RequestInfo | URL): number | undefined => {
+    const url = new URL(String(input));
+    return url.hostname === "files.ente.io"
+        ? Number(url.searchParams.get("fileID"))
+        : undefined;
+};
+
+// The fake server, pushing onto `downloads` the ID of each file whose original
+// is downloaded.
+const recordingDownloads =
+    (downloads: number[]): typeof globalThis.fetch =>
+    async (input, init) => {
+        const fileID = downloadOf(input);
+        if (fileID !== undefined) downloads.push(fileID);
+        return server(input, init);
+    };
+
+// Every entry under `dir`, relative to it, sorted, a symlink as
+// `name -> target`.
+const listTree = (dir: string): string[] =>
+    readdirSync(dir, { recursive: true })
+        .sort()
+        .map((name) => {
+            const path = join(dir, name);
+            return lstatSync(path).isSymbolicLink()
+                ? `${name} -> ${readlinkSync(path)}`
+                : name;
+        });
+
+const readJSON = (path: string) => JSON.parse(readFileSync(path, "utf-8"));
+
+describe("the first backup of the account", () => {
+    let dir: string;
+    let code: number;
+    const downloads: number[] = [];
+
+    beforeAll(async () => {
+        dir = mkdtempSync(join(root, "backup-"));
+        ({ code } = await backup(dir, {}, recordingDownloads(downloads)));
+    });
+
+    it("exits 0, having downloaded each file once", () => {
+        expect(code).toBe(0);
+        // beach.jpg is in two albums but is downloaded, and stored, once.
+        expect(downloads.sort()).toEqual([100, 200, 300]);
+    });
+
+    // The tree "Backup layout" in the README describes. Each original is at
+    // its save path, `YYYY/YYYY-MM/YYYY-MM-DD/YYYY-MM-DD.<fileID>.<ext>`, with
+    // the extension of its title; the live photo is its image and its video,
+    // each with the extension it had inside the ZIP, and a `.livephoto.json`
+    // naming the two. Beside each original is its JSON. Each album is a
+    // folder of links named after the files' titles, with a JSON file beside
+    // it. No file failed, so there is no `failures.json`, and the run removed
+    // its lock, `backup.lock`, as it ended.
+    it("lays the backup out as the README describes", () => {
+        expect(listTree(dir)).toEqual([
+            "2024",
+            "2024/2024-03",
+            "2024/2024-03/2024-03-01",
+            "2024/2024-03/2024-03-01/2024-03-01.100.jpg",
+            "2024/2024-03/2024-03-01/2024-03-01.100.json",
+            "2024/2024-03/2024-03-01/2024-03-01.200.json",
+            "2024/2024-03/2024-03-01/2024-03-01.200.mp4",
+            "2024/2024-03/2024-03-01/2024-03-01.300.heic",
+            "2024/2024-03/2024-03-01/2024-03-01.300.json",
+            "2024/2024-03/2024-03-01/2024-03-01.300.livephoto.json",
+            "2024/2024-03/2024-03-01/2024-03-01.300.mov",
+            "account.json",
+            "collections",
+            "collections/Family",
+            "collections/Family.json",
+            "collections/Family/IMG_0002.heic -> ../../2024/2024-03/2024-03-01/2024-03-01.300.heic",
+            "collections/Family/IMG_0002.mov -> ../../2024/2024-03/2024-03-01/2024-03-01.300.mov",
+            "collections/Family/beach.jpg -> ../../2024/2024-03/2024-03-01/2024-03-01.100.jpg",
+            "collections/Friend's Wedding",
+            "collections/Friend's Wedding.json",
+            "collections/Friend's Wedding/toast.mp4 -> ../../2024/2024-03/2024-03-01/2024-03-01.200.mp4",
+            "collections/Trips",
+            "collections/Trips.json",
+            "collections/Trips/beach.jpg -> ../../2024/2024-03/2024-03-01/2024-03-01.100.jpg",
+        ]);
+    });
+
+    it("stores each original decrypted, a live photo as its image and its video", () => {
+        const day = join(dir, DAY);
+        expect(readFileSync(join(day, "2024-03-01.100.jpg"))).toEqual(
+            Buffer.from(JPEG_WITH_EXIF),
+        );
+        expect(readFileSync(join(day, "2024-03-01.200.mp4"))).toEqual(
+            Buffer.from(TOAST),
+        );
+        expect(readFileSync(join(day, "2024-03-01.300.heic"))).toEqual(
+            Buffer.from(HEIC_WITH_EXIF),
+        );
+        expect(readFileSync(join(day, "2024-03-01.300.mov"))).toEqual(
+            Buffer.from(VIDEO),
+        );
+        expect(readJSON(join(day, "2024-03-01.300.livephoto.json"))).toEqual({
+            image: "2024-03-01.300.heic",
+            video: "2024-03-01.300.mov",
+        });
+    });
+
+    // A file's JSON holds what Ente records for it, decrypted, and what quak
+    // read from its original: its ML data when Ente has any, and, for an
+    // image, its EXIF. A video gets no image metadata.
+    it("writes each file's JSON with its ML data and image metadata", () => {
+        const day = join(dir, DAY);
+
+        const beach = readJSON(join(day, "2024-03-01.100.json"));
+        expect(beach).toMatchObject({
+            id: 100,
+            ownerID: USER_ID,
+            metadata: {
+                title: "beach.jpg",
+                fileType: "image",
+                creationTime: TAKEN,
+                hash: BEACH.metadata.hash,
+            },
+            updationTime: TAKEN,
+        });
+        expect(beach.mlData).toEqual(ML_DATA);
+        expect(beach.imageMetadata.exif.Make.description).toBe("Canon");
+        expect(beach.imageMetadata.exif.Model.description).toBe("EOS R5");
+
+        const toast = readJSON(join(day, "2024-03-01.200.json"));
+        expect(toast).toMatchObject({
+            id: 200,
+            ownerID: FRIEND_ID,
+            metadata: { title: "toast.mp4", fileType: "video" },
+        });
+        expect(toast).not.toHaveProperty("mlData");
+        expect(toast).not.toHaveProperty("imageMetadata");
+        expect(toast).not.toHaveProperty("imageMetadataError");
+
+        // A live photo's image metadata is read from its image.
+        const livePhoto = readJSON(join(day, "2024-03-01.300.json"));
+        expect(livePhoto).toMatchObject({
+            id: 300,
+            ownerID: USER_ID,
+            metadata: {
+                title: "IMG_0002.HEIC",
+                fileType: "livePhoto",
+                hash: LIVE_PHOTO.metadata.hash,
+            },
+        });
+        expect(livePhoto.imageMetadata.exif.Make.description).toBe("Canon");
+    });
+
+    it("writes each album's JSON and the account's", () => {
+        const albumJSON = (name: string) =>
+            readJSON(join(dir, "collections", `${name}.json`));
+        const fileIDs = (album: { files: { id: number }[] }) =>
+            album.files.map((f) => f.id);
+
+        const trips = albumJSON("Trips");
+        expect(trips).toMatchObject({
+            id: 10,
+            name: "Trips",
+            type: "album",
+            ownerID: USER_ID,
+            isShared: false,
+            updationTime: TAKEN,
+        });
+        expect(fileIDs(trips)).toEqual([100]);
+
+        const family = albumJSON("Family");
+        expect(family).toMatchObject({ id: 20, isShared: false });
+        expect(fileIDs(family)).toEqual([100, 300]);
+
+        const wedding = albumJSON("Friend's Wedding");
+        expect(wedding).toMatchObject({
+            id: 30,
+            ownerID: FRIEND_ID,
+            isShared: true,
+        });
+        expect(fileIDs(wedding)).toEqual([200]);
+
+        expect(readJSON(join(dir, "account.json"))).toEqual({
+            email: EMAIL,
+            userID: USER_ID,
+        });
+    });
+});
+
+describe("quak backup", () => {
+    // An original already at its save path is complete, so a later run, such
+    // as the next night's from cron, only rewrites the JSON files and the
+    // album links.
+    it("downloads nothing on a second run, and exits 0", async () => {
+        const dir = mkdtempSync(join(root, "backup-"));
+        expect((await backup(dir)).code).toBe(0);
+        const firstTree = listTree(dir);
+
+        const downloads: number[] = [];
+        const { code } = await backup(dir, {}, recordingDownloads(downloads));
+        expect(code).toBe(0);
+        expect(downloads).toEqual([]);
+        expect(listTree(dir)).toEqual(firstTree);
+    });
+
+    // The files CDN is briefly unavailable for toast.mp4: its first two
+    // downloads answer 503. A 5xx is worth repeating, so quak tries again,
+    // here without waiting, and the third download succeeds.
+    it("stores a file whose download fails twice with 503 and then succeeds, and exits 0", async () => {
+        let attempts = 0;
+        const fetch: typeof globalThis.fetch = async (input, init) => {
+            if (downloadOf(input) === 200 && ++attempts <= 2) {
+                return new Response("unavailable", { status: 503 });
+            }
+            return server(input, init);
+        };
+        const dir = mkdtempSync(join(root, "backup-"));
+
+        const { code } = await backup(dir, {}, fetch);
+
+        expect(code).toBe(0);
+        expect(attempts).toBe(3);
+        expect(readFileSync(join(dir, DAY, "2024-03-01.200.mp4"))).toEqual(
+            Buffer.from(TOAST),
+        );
+        expect(existsSync(join(dir, "failures.json"))).toBe(false);
+    });
+
+    // The server answers 404 for toast.mp4 on every try. A 404 is an answer,
+    // not a hiccup, so quak does not repeat it: the file goes into
+    // `failures.json` with the kind of failure, how many times it has been
+    // tried and why, the backup goes on with the other files, and the exit
+    // code is 1, so the next run tries again.
+    it("records a file whose download always answers 404 in failures.json, stores the rest, and exits 1", async () => {
+        let attempts = 0;
+        const fetch: typeof globalThis.fetch = async (input, init) => {
+            if (downloadOf(input) === 200) {
+                attempts++;
+                return new Response("not found", { status: 404 });
+            }
+            return server(input, init);
+        };
+        const dir = mkdtempSync(join(root, "backup-"));
+
+        const { code, stderr } = await backup(dir, {}, fetch);
+
+        expect(code).toBe(1);
+        expect(attempts).toBe(1);
+        const failures = readJSON(join(dir, "failures.json"));
+        expect(Object.keys(failures.files)).toEqual(["200"]);
+        expect(failures.files["200"]).toMatchObject({
+            fileID: 200,
+            title: "toast.mp4",
+            classification: "permanent",
+            attempts: 1,
+        });
+        expect(failures.files["200"].error).toContain("404");
+        expect(stderr).toContain("[Friend's Wedding] toast.mp4 (id 200): ");
+
+        // The rest of the account is backed up; the video is not, and its
+        // album folder has no link to it.
+        expect(readFileSync(join(dir, DAY, "2024-03-01.100.jpg"))).toEqual(
+            Buffer.from(JPEG_WITH_EXIF),
+        );
+        expect(readFileSync(join(dir, DAY, "2024-03-01.300.heic"))).toEqual(
+            Buffer.from(HEIC_WITH_EXIF),
+        );
+        expect(existsSync(join(dir, DAY, "2024-03-01.200.mp4"))).toBe(false);
+        expect(
+            readdirSync(join(dir, "collections", "Friend's Wedding")),
+        ).toEqual([]);
+    });
+
+    // The server no longer accepts the saved session's token, as after
+    // `quak logout` elsewhere, and answers every request with 401. The run
+    // stops at the refresh it starts with, says to log in again, and exits 3.
+    // It took its lock first, so every request was sent while the lock was
+    // there, and it removed the lock as it ended: the directory is left as it
+    // was, empty.
+    it("exits 3 when the refresh is answered with 401, writing nothing but the lock", async () => {
+        const dir = mkdtempSync(join(root, "backup-"));
+        const lockAtEachRequest: boolean[] = [];
+        const fetch: typeof globalThis.fetch = async () => {
+            lockAtEachRequest.push(existsSync(join(dir, "backup.lock")));
+            return new Response(null, { status: 401 });
+        };
+
+        const { code, stderr } = await backup(dir, {}, fetch);
+
+        expect(code).toBe(3);
+        expect(stderr).toBe(
+            "Starting backup...\n" +
+                "Refreshing library...\n" +
+                `quak: the saved session is no longer valid; run "quak login"\n`,
+        );
+        expect(lockAtEachRequest).not.toHaveLength(0);
+        expect(lockAtEachRequest).not.toContain(false);
+        expect(readdirSync(dir)).toEqual([]);
+    });
+
+    // Something changed beach.jpg on disk after it was backed up. A run with
+    // --verify hashes every stored original, finds that one no longer matches
+    // the hash Ente recorded, says so, and downloads it again; it put back the
+    // right bytes, so the exit code is 0.
+    it("--verify puts back an original that changed on disk, and exits 0", async () => {
+        const dir = mkdtempSync(join(root, "backup-"));
+        expect((await backup(dir)).code).toBe(0);
+        const beach = join(dir, DAY, "2024-03-01.100.jpg");
+        writeFileSync(beach, "not the photo any more");
+
+        const downloads: number[] = [];
+        const { code, stderr } = await backup(
+            dir,
+            { verify: true },
+            recordingDownloads(downloads),
+        );
+
+        expect(code).toBe(0);
+        expect(downloads).toEqual([100]);
+        expect(readFileSync(beach)).toEqual(Buffer.from(JPEG_WITH_EXIF));
+        expect(stderr).toContain(
+            "MISMATCH original beach.jpg (100): its bytes do not match its content hash",
+        );
+        expect(stderr).toContain("  Verified:    2\n  Mismatched:  1\n");
+    });
+});

test/cli/metadata-backup.test.ts

@@ -37,15 +37,8 @@ import {
 import { join } from "node:path";
 import { tmpdir } from "node:os";
 import sodium from "libsodium-wrappers-sumo";
-import { SRP, SrpServer } from "fast-srp-hap";
 import { beforeAll, afterAll, describe, expect, it, vi } from "vitest";
-import {
+import { init, toBase64, encryptBlob } from "../../src/crypto/index.js";
-    init,
-    toBase64,
-    deriveKEK,
-    deriveLoginSubkey,
-    encryptBlob,
-} from "../../src/crypto/index.js";
 import * as jpegJs from "jpeg-js";
 import { Client } from "../../src/client.js";
 import { Library } from "../../src/library/index.js";
@@ -54,7 +47,13 @@ import {
     type MetadataBackupOptions,
 } from "../../src/metadata-backup.js";
 import { backupMetadataCommand } from "../../src/cli-commands.js";
-import type { KeyAttributes } from "../../src/auth/types.js";
+import {
+    buildAccount,
+    buildMetaFetch,
+    encryptSecretbox,
+    encryptStreamBlob,
+    type MetaMockState,
+} from "../ente-server.js";
 
 // One file per ML data request, so the two files of the mock account are
 // fetched in two requests and one of them can fail on its own.
@@ -65,80 +64,13 @@ vi.mock("../../src/mldata-fetch.js", async (importOriginal) => ({
 
 const TEST_EMAIL = "metabackup@example.com";
 const TEST_PASSWORD = "metapass";
-const TEST_OPS = 2;
-const TEST_MEM = 64 * 1024 * 1024;
-
-interface MetaMockState {
-    verifier: Buffer;
-    srpAttributes: Record<string, unknown>;
-    keyAttributes: KeyAttributes;
-    encryptedToken: string;
-    collections: Record<string, unknown>[];
-    filesByCollection: Record<number, Record<string, unknown>[]>;
-    // For ML data and EXIF tests
-    encryptedMLData: Record<
-        number,
-        { encryptedData: string; decryptionHeader: string }
-    >;
-    fileCiphertexts: Record<number, Uint8Array>;
-}
 
 let mock: MetaMockState;
 let testDir: string;
 
-const encryptSecretbox = (plaintext: Uint8Array, key: Uint8Array) => {
-    const nonce = sodium.randombytes_buf(sodium.crypto_secretbox_NONCEBYTES);
-    const ciphertext = sodium.crypto_secretbox_easy(plaintext, nonce, key);
-    return { ciphertext, nonce };
-};
-
-const encryptStreamBlob = (plaintext: Uint8Array, key: Uint8Array) => {
-    const push = sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
-    const ciphertext = sodium.crypto_secretstream_xchacha20poly1305_push(
-        push.state,
-        plaintext,
-        null,
-        sodium.crypto_secretstream_xchacha20poly1305_TAG_FINAL,
-    );
-    return { ciphertext, header: push.header };
-};
-
 const buildMetaMock = async (): Promise<MetaMockState> => {
-    const kekSalt = sodium.randombytes_buf(sodium.crypto_pwhash_SALTBYTES);
+    const account = await buildAccount(TEST_PASSWORD);
-    const kek = await deriveKEK(TEST_PASSWORD, kekSalt, TEST_OPS, TEST_MEM);
+    const masterKey = account.masterKey;
-    const loginSubKeyBytes = deriveLoginSubkey(kek);
-    const srpUserID = "meta-srp";
-    const srpSalt = sodium.randombytes_buf(16);
-    const verifier = SRP.computeVerifier(
-        SRP.params["4096"],
-        Buffer.from(srpSalt),
-        Buffer.from(srpUserID),
-        Buffer.from(loginSubKeyBytes),
-    );
-
-    const masterKey = sodium.randombytes_buf(32);
-    const { ciphertext: encMK, nonce: mkNonce } = encryptSecretbox(
-        masterKey,
-        kek,
-    );
-    const kp = sodium.crypto_box_keypair();
-    const { ciphertext: encSK, nonce: skNonce } = encryptSecretbox(
-        kp.privateKey,
-        masterKey,
-    );
-    const tokenBytes = sodium.randombytes_buf(32);
-    const encToken = sodium.crypto_box_seal(tokenBytes, kp.publicKey);
-
-    const keyAttributes: KeyAttributes = {
-        kekSalt: toBase64(kekSalt),
-        encryptedKey: toBase64(encMK),
-        keyDecryptionNonce: toBase64(mkNonce),
-        publicKey: toBase64(kp.publicKey),
-        encryptedSecretKey: toBase64(encSK),
-        secretKeyDecryptionNonce: toBase64(skNonce),
-        memLimit: TEST_MEM,
-        opsLimit: TEST_OPS,
-    };
 
     // Collection 1: "Vacation" with collection-level pubMagicMetadata
     const ck1 = sodium.crypto_secretbox_keygen();
@@ -332,17 +264,10 @@ const buildMetaMock = async (): Promise<MetaMockState> => {
     rawFile1.file.decryptionHeader = toBase64(filePush1.header);
 
     return {
-        verifier,
+        verifier: account.verifier,
-        srpAttributes: {
+        srpAttributes: account.srpAttributes,
-            srpUserID,
+        keyAttributes: account.keyAttributes,
-            srpSalt: toBase64(srpSalt),
+        encryptedToken: account.encryptedToken,
-            memLimit: TEST_MEM,
-            opsLimit: TEST_OPS,
-            kekSalt: toBase64(kekSalt),
-            isEmailMFAEnabled: false,
-        },
-        keyAttributes,
-        encryptedToken: toBase64(encToken),
         collections: [rawColl1, rawColl2],
         filesByCollection: { 10: [rawFile1], 20: [rawFile2] },
         encryptedMLData: {
@@ -355,90 +280,6 @@ const buildMetaMock = async (): Promise<MetaMockState> => {
     };
 };
 
-// `failMLDataFor`: answer 500 to every ML data request that asks for this file.
-const buildMetaFetch = (m: MetaMockState, failMLDataFor?: number) => {
-    let srpServer: SrpServer;
-    return (async (
-        input: RequestInfo | URL,
-        init?: RequestInit,
-    ): Promise<Response> => {
-        const url =
-            typeof input === "string"
-                ? input
-                : input instanceof URL
-                  ? input.href
-                  : input.url;
-        const path = new URL(url).pathname;
-        const json = (body: unknown) =>
-            new Response(JSON.stringify(body), {
-                status: 200,
-                headers: { "content-type": "application/json" },
-            });
-
-        if (path === "/users/srp/attributes")
-            return json({ attributes: m.srpAttributes });
-        if (path === "/users/srp/create-session") {
-            const body = JSON.parse(init?.body as string);
-            const serverKey = await SRP.genKey();
-            srpServer = new SrpServer(
-                SRP.params["4096"],
-                m.verifier,
-                serverKey,
-            );
-            const B = srpServer.computeB();
-            srpServer.setA(Buffer.from(body.srpA, "base64"));
-            return json({ sessionID: "s1", srpB: B.toString("base64") });
-        }
-        if (path === "/users/srp/verify-session") {
-            const body = JSON.parse(init?.body as string);
-            srpServer.checkM1(Buffer.from(body.srpM1, "base64"));
-            return json({
-                srpM2: srpServer.computeM2().toString("base64"),
-                id: 42,
-                keyAttributes: m.keyAttributes,
-                encryptedToken: m.encryptedToken,
-            });
-        }
-        if (path === "/collections/v2")
-            return json({ collections: m.collections });
-        if (path === "/collections/v2/diff") {
-            const collID = Number(
-                new URL(url).searchParams.get("collectionID"),
-            );
-            return json({
-                diff: m.filesByCollection[collID] ?? [],
-                hasMore: false,
-            });
-        }
-        if (path === "/files/data/fetch") {
-            const body = JSON.parse(init?.body as string);
-            if ((body.fileIDs as number[]).includes(failMLDataFor!))
-                return new Response("server error", { status: 500 });
-            const data = (body.fileIDs as number[])
-                .filter((id: number) => m.encryptedMLData[id])
-                .map((id: number) => ({
-                    fileID: id,
-                    ...m.encryptedMLData[id],
-                    updatedAt: 1700000000000000,
-                }));
-            return json({ data });
-        }
-        if (
-            url.includes("files.ente.io") ||
-            path.startsWith("/files/download/")
-        ) {
-            const parsed = new URL(url);
-            const fileID = Number(
-                parsed.searchParams.get("fileID") ?? path.split("/").pop(),
-            );
-            const ct = m.fileCiphertexts[fileID];
-            if (ct) return new Response(ct, { status: 200 });
-            return new Response("not found", { status: 404 });
-        }
-        return new Response("not found", { status: 404 });
-    }) as typeof globalThis.fetch;
-};
-
 beforeAll(async () => {
     await init();
     await sodium.ready;

test/ente-server.ts

@@ -0,0 +1,197 @@
+/**
+ * A fake of the Ente HTTP API, for tests that run quak's real `Client` against
+ * a server.
+ *
+ * `buildMetaFetch` is a `fetch` that answers the requests quak makes, from a
+ * `MetaMockState` the test builds: the SRP login, `/collections/v2`, each
+ * collection's `/collections/v2/diff`, the ML data of `/files/data/fetch`, and
+ * each file's content from the files CDN, a 404 for a file it holds none for.
+ * The test encrypts everything in that state with libsodium, as Ente's clients
+ * do, so quak decrypts it with its own code. Nothing hits the network.
+ *
+ * `buildAccount` builds what the server holds to log an account in, and the
+ * keys a test encrypts that account's collections with. Call `init()` from
+ * `src/crypto` and await `sodium.ready` before using either.
+ */
+
+import sodium from "libsodium-wrappers-sumo";
+import { SRP, SrpServer } from "fast-srp-hap";
+import { toBase64, deriveKEK, deriveLoginSubkey } from "../src/crypto/index.js";
+import type { KeyAttributes } from "../src/auth/types.js";
+
+const TEST_OPS = 2;
+const TEST_MEM = 64 * 1024 * 1024;
+
+export interface MetaMockState {
+    verifier: Buffer;
+    srpAttributes: Record<string, unknown>;
+    keyAttributes: KeyAttributes;
+    encryptedToken: string;
+    collections: Record<string, unknown>[];
+    filesByCollection: Record<number, Record<string, unknown>[]>;
+    // For ML data and EXIF tests
+    encryptedMLData: Record<
+        number,
+        { encryptedData: string; decryptionHeader: string }
+    >;
+    fileCiphertexts: Record<number, Uint8Array>;
+}
+
+export const encryptSecretbox = (plaintext: Uint8Array, key: Uint8Array) => {
+    const nonce = sodium.randombytes_buf(sodium.crypto_secretbox_NONCEBYTES);
+    const ciphertext = sodium.crypto_secretbox_easy(plaintext, nonce, key);
+    return { ciphertext, nonce };
+};
+
+export const encryptStreamBlob = (plaintext: Uint8Array, key: Uint8Array) => {
+    const push = sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
+    const ciphertext = sodium.crypto_secretstream_xchacha20poly1305_push(
+        push.state,
+        plaintext,
+        null,
+        sodium.crypto_secretstream_xchacha20poly1305_TAG_FINAL,
+    );
+    return { ciphertext, header: push.header };
+};
+
+// An account whose password is `password`. The first four fields are those of
+// `MetaMockState`; with the master key the test encrypts the keys of the
+// account's own collections, and to the public key it seals the keys of the
+// collections other accounts share with it.
+export const buildAccount = async (password: string) => {
+    const kekSalt = sodium.randombytes_buf(sodium.crypto_pwhash_SALTBYTES);
+    const kek = await deriveKEK(password, kekSalt, TEST_OPS, TEST_MEM);
+    const loginSubKeyBytes = deriveLoginSubkey(kek);
+    const srpUserID = "meta-srp";
+    const srpSalt = sodium.randombytes_buf(16);
+    const verifier = SRP.computeVerifier(
+        SRP.params["4096"],
+        Buffer.from(srpSalt),
+        Buffer.from(srpUserID),
+        Buffer.from(loginSubKeyBytes),
+    );
+
+    const masterKey = sodium.randombytes_buf(32);
+    const { ciphertext: encMK, nonce: mkNonce } = encryptSecretbox(
+        masterKey,
+        kek,
+    );
+    const kp = sodium.crypto_box_keypair();
+    const { ciphertext: encSK, nonce: skNonce } = encryptSecretbox(
+        kp.privateKey,
+        masterKey,
+    );
+    const tokenBytes = sodium.randombytes_buf(32);
+    const encToken = sodium.crypto_box_seal(tokenBytes, kp.publicKey);
+
+    const keyAttributes: KeyAttributes = {
+        kekSalt: toBase64(kekSalt),
+        encryptedKey: toBase64(encMK),
+        keyDecryptionNonce: toBase64(mkNonce),
+        publicKey: toBase64(kp.publicKey),
+        encryptedSecretKey: toBase64(encSK),
+        secretKeyDecryptionNonce: toBase64(skNonce),
+        memLimit: TEST_MEM,
+        opsLimit: TEST_OPS,
+    };
+
+    return {
+        verifier,
+        srpAttributes: {
+            srpUserID,
+            srpSalt: toBase64(srpSalt),
+            memLimit: TEST_MEM,
+            opsLimit: TEST_OPS,
+            kekSalt: toBase64(kekSalt),
+            isEmailMFAEnabled: false,
+        },
+        keyAttributes,
+        encryptedToken: toBase64(encToken),
+        masterKey,
+        publicKey: kp.publicKey,
+    };
+};
+
+// `failMLDataFor`: answer 500 to every ML data request that asks for this file.
+export const buildMetaFetch = (m: MetaMockState, failMLDataFor?: number) => {
+    let srpServer: SrpServer;
+    return (async (
+        input: RequestInfo | URL,
+        init?: RequestInit,
+    ): Promise<Response> => {
+        const url =
+            typeof input === "string"
+                ? input
+                : input instanceof URL
+                  ? input.href
+                  : input.url;
+        const path = new URL(url).pathname;
+        const json = (body: unknown) =>
+            new Response(JSON.stringify(body), {
+                status: 200,
+                headers: { "content-type": "application/json" },
+            });
+
+        if (path === "/users/srp/attributes")
+            return json({ attributes: m.srpAttributes });
+        if (path === "/users/srp/create-session") {
+            const body = JSON.parse(init?.body as string);
+            const serverKey = await SRP.genKey();
+            srpServer = new SrpServer(
+                SRP.params["4096"],
+                m.verifier,
+                serverKey,
+            );
+            const B = srpServer.computeB();
+            srpServer.setA(Buffer.from(body.srpA, "base64"));
+            return json({ sessionID: "s1", srpB: B.toString("base64") });
+        }
+        if (path === "/users/srp/verify-session") {
+            const body = JSON.parse(init?.body as string);
+            srpServer.checkM1(Buffer.from(body.srpM1, "base64"));
+            return json({
+                srpM2: srpServer.computeM2().toString("base64"),
+                id: 42,
+                keyAttributes: m.keyAttributes,
+                encryptedToken: m.encryptedToken,
+            });
+        }
+        if (path === "/collections/v2")
+            return json({ collections: m.collections });
+        if (path === "/collections/v2/diff") {
+            const collID = Number(
+                new URL(url).searchParams.get("collectionID"),
+            );
+            return json({
+                diff: m.filesByCollection[collID] ?? [],
+                hasMore: false,
+            });
+        }
+        if (path === "/files/data/fetch") {
+            const body = JSON.parse(init?.body as string);
+            if ((body.fileIDs as number[]).includes(failMLDataFor!))
+                return new Response("server error", { status: 500 });
+            const data = (body.fileIDs as number[])
+                .filter((id: number) => m.encryptedMLData[id])
+                .map((id: number) => ({
+                    fileID: id,
+                    ...m.encryptedMLData[id],
+                    updatedAt: 1700000000000000,
+                }));
+            return json({ data });
+        }
+        if (
+            url.includes("files.ente.io") ||
+            path.startsWith("/files/download/")
+        ) {
+            const parsed = new URL(url);
+            const fileID = Number(
+                parsed.searchParams.get("fileID") ?? path.split("/").pop(),
+            );
+            const ct = m.fileCiphertexts[fileID];
+            if (ct) return new Response(ct, { status: 200 });
+            return new Response("not found", { status: 404 });
+        }
+        return new Response("not found", { status: 404 });
+    }) as typeof globalThis.fetch;
+};