Switch crypto.spec.ts away from TestClient and matrix-mock-request. (#3142)

I became sufficiently annoyed with matrix-mock-request that I decided to replace it with fetch-mock, which is what we use in matrix-react-sdk and is generally more powerful, easier to use, and actually maintained.

Unfortunately, we have a TestClient utility which is widely used and quite tightly integrated with matrix-mock-request. It wasn't going to be possible to change TestClient without changing all the tests that use it.

I also don't find TestClient particularly easy to use - it does a lot of stuff which I'm not convinced ought to be done for every single test.

So... I've introduced a couple of new classes (SyncResponder, E2EKeyReceiver) which do some of the useful bits of TestClient, but in a more granular way, and have switched crypto.spec.ts over so that rather than instantiating a TestClient for each test, it creates a MatrixClient directly and intercepts the endpoints necessary.

spec/test-utils/E2EKeyReceiver.ts

@@ -0,0 +1,159 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import debugFunc from "debug";
+import { Debugger } from "debug";
+import fetchMock from "fetch-mock-jest";
+
+import type { IDeviceKeys, IOneTimeKey } from "../../src/@types/crypto";
+
+/** Interface implemented by classes that intercept `/keys/upload` requests from test clients to catch the uploaded keys
+ *
+ * Common interface implemented by {@link TestClient} and {@link E2EKeyReceiver}
+ */
+export interface IE2EKeyReceiver {
+    /**
+     * get the uploaded ed25519 device key
+     *
+     * @returns base64 device key
+     */
+    getSigningKey(): string;
+
+    /**
+     * get the uploaded curve25519 device key
+     *
+     * @returns base64 device key
+     */
+    getDeviceKey(): string;
+
+    /**
+     * Wait for one-time-keys to be uploaded, then return them.
+     *
+     * @returns Promise for the one-time keys
+     */
+    awaitOneTimeKeyUpload(): Promise<Record<string, IOneTimeKey>>;
+}
+
+/** E2EKeyReceiver: An object which intercepts `/keys/uploads` fetches via fetch-mock.
+ *
+ * It stashes the uploaded keys for use elsewhere in the tests.
+ */
+export class E2EKeyReceiver implements IE2EKeyReceiver {
+    private readonly debug: Debugger;
+
+    private deviceKeys: IDeviceKeys | null = null;
+    private oneTimeKeys: Record<string, IOneTimeKey> = {};
+    private readonly oneTimeKeysPromise: Promise<void>;
+
+    /**
+     * Construct a new E2EKeyReceiver.
+     *
+     * It will immediately register an intercept of `/keys/uploads` requests for the given homeserverUrl.
+     * Only /upload requests made to this server will be intercepted: this allows a single test to use more than one
+     * client and have the keys collected separately.
+     *
+     * @param homeserverUrl - the Homeserver Url of the client under test.
+     */
+    public constructor(homeserverUrl: string) {
+        this.debug = debugFunc(`e2e-key-receiver:[${homeserverUrl}]`);
+
+        // set up a listener for /keys/upload.
+        this.oneTimeKeysPromise = new Promise((resolveOneTimeKeys) => {
+            const listener = (url: string, options: RequestInit) =>
+                this.onKeyUploadRequest(resolveOneTimeKeys, options);
+
+            // catch both r0 and v3 variants
+            fetchMock.post(new URL("/_matrix/client/r0/keys/upload", homeserverUrl).toString(), listener);
+            fetchMock.post(new URL("/_matrix/client/v3/keys/upload", homeserverUrl).toString(), listener);
+        });
+    }
+
+    private async onKeyUploadRequest(onOnTimeKeysUploaded: () => void, options: RequestInit): Promise<object> {
+        const content = JSON.parse(options.body as string);
+
+        // device keys may only be uploaded once
+        if (content.device_keys && Object.keys(content.device_keys).length > 0) {
+            if (this.deviceKeys) {
+                throw new Error("Application attempted to upload E2E device keys multiple times");
+            }
+            this.debug(`received device keys`);
+            this.deviceKeys = content.device_keys;
+        }
+
+        if (content.one_time_keys && Object.keys(content.one_time_keys).length > 0) {
+            // this is a one-time-key upload
+
+            // if we already have a batch of one-time keys, then slow-roll the response,
+            // otherwise the client ends up tight-looping one-time-key-uploads and filling the logs with junk.
+            if (Object.keys(this.oneTimeKeys).length > 0) {
+                this.debug(`received second batch of one-time keys: blocking response`);
+                await new Promise(() => {});
+            }
+
+            this.debug(`received ${Object.keys(content.one_time_keys).length} one-time keys`);
+            Object.assign(this.oneTimeKeys, content.one_time_keys);
+            onOnTimeKeysUploaded();
+        }
+
+        return {
+            one_time_key_counts: {
+                signed_curve25519: Object.keys(this.oneTimeKeys).length,
+            },
+        };
+    }
+
+    /** Get the uploaded Ed25519 key
+     *
+     * If device keys have not yet been uploaded, throws an error
+     */
+    public getSigningKey(): string {
+        if (!this.deviceKeys) {
+            throw new Error("Device keys not yet uploaded");
+        }
+        const keyIds = Object.keys(this.deviceKeys.keys).filter((v) => v.startsWith("ed25519:"));
+        if (keyIds.length != 1) {
+            throw new Error(`Expected exactly 1 ed25519 key uploaded, got ${keyIds}`);
+        }
+        return this.deviceKeys.keys[keyIds[0]];
+    }
+
+    /** Get the uploaded Curve25519 key
+     *
+     * If device keys have not yet been uploaded, throws an error
+     */
+    public getDeviceKey(): string {
+        if (!this.deviceKeys) {
+            throw new Error("Device keys not yet uploaded");
+        }
+        const keyIds = Object.keys(this.deviceKeys.keys).filter((v) => v.startsWith("curve25519:"));
+        if (keyIds.length != 1) {
+            throw new Error(`Expected exactly 1 curve25519 key uploaded, got ${keyIds}`);
+        }
+        return this.deviceKeys.keys[keyIds[0]];
+    }
+
+    /**
+     * If one-time keys have already been uploaded, return them. Otherwise,
+     * set up an expectation that the keys will be uploaded, and wait for
+     * that to happen.
+     *
+     * @returns Promise for the one-time keys
+     */
+    public async awaitOneTimeKeyUpload(): Promise<Record<string, IOneTimeKey>> {
+        await this.oneTimeKeysPromise;
+        return this.oneTimeKeys;
+    }
+}