Improve typing around event emitter handlers (#2180)

Author: t3chguy

.eslintrc.js

@@ -31,6 +31,9 @@ module.exports = {
         "no-async-promise-executor": "off",
         // We use a `logger` intermediary module
         "no-console": "error",
+
+        // restrict EventEmitters to force callers to use TypedEventEmitter
+        "no-restricted-imports": ["error", "events"],
     },
     overrides: [{
         files: [

spec/integ/matrix-client-retrying.spec.ts

@@ -1,4 +1,4 @@
-import { EventStatus } from "../../src/matrix";
+import { EventStatus, RoomEvent } from "../../src/matrix";
 import { MatrixScheduler } from "../../src/scheduler";
 import { Room } from "../../src/models/room";
 import { TestClient } from "../TestClient";
@@ -95,7 +95,7 @@ describe("MatrixClient retrying", function() {
 
         // wait for the localecho of ev1 to be updated
         const p3 = new Promise<void>((resolve, reject) => {
-            room.on("Room.localEchoUpdated", (ev0) => {
+            room.on(RoomEvent.LocalEchoUpdated, (ev0) => {
                 if (ev0 === ev1) {
                     resolve();
                 }

spec/unit/ReEmitter.spec.ts

@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// eslint-disable-next-line no-restricted-imports
 import { EventEmitter } from "events";
 
 import { ReEmitter } from "../../src/ReEmitter";

spec/unit/crypto.spec.js

@@ -1,4 +1,5 @@
 import '../olm-loader';
+// eslint-disable-next-line no-restricted-imports
 import { EventEmitter } from "events";
 
 import { Crypto } from "../../src/crypto";

spec/unit/crypto/crypto-utils.js

@@ -26,7 +26,7 @@ export async function resetCrossSigningKeys(client, {
         crypto.crossSigningInfo.keys = oldKeys;
         throw e;
     }
-    crypto.baseApis.emit("crossSigning.keysChanged", {});
+    crypto.emit("crossSigning.keysChanged", {});
     await crypto.afterCrossSigningLocalKeyChange();
 }
 

spec/unit/crypto/verification/secret_request.spec.js

@@ -14,10 +14,10 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { VerificationBase } from '../../../../src/crypto/verification/Base';
 import { CrossSigningInfo } from '../../../../src/crypto/CrossSigning';
 import { encodeBase64 } from "../../../../src/crypto/olmlib";
 import { setupWebcrypto, teardownWebcrypto } from './util';
+import { VerificationBase } from '../../../../src/crypto/verification/Base';
 
 jest.useFakeTimers();
 

spec/unit/relations.spec.ts

@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import { EventTimelineSet } from "../../src/models/event-timeline-set";
-import { MatrixEvent } from "../../src/models/event";
+import { MatrixEvent, MatrixEventEvent } from "../../src/models/event";
 import { Room } from "../../src/models/room";
 import { Relations } from "../../src/models/relations";
 
@@ -103,7 +103,7 @@ describe("Relations", function() {
         // Add the target event first, then the relation event
         {
             const relationsCreated = new Promise(resolve => {
-                targetEvent.once("Event.relationsCreated", resolve);
+                targetEvent.once(MatrixEventEvent.RelationsCreated, resolve);
             });
 
             const timelineSet = new EventTimelineSet(room, {
@@ -118,7 +118,7 @@ describe("Relations", function() {
         // Add the relation event first, then the target event
         {
             const relationsCreated = new Promise(resolve => {
-                targetEvent.once("Event.relationsCreated", resolve);
+                targetEvent.once(MatrixEventEvent.RelationsCreated, resolve);
             });
 
             const timelineSet = new EventTimelineSet(room, {

src/ReEmitter.ts

@@ -16,16 +16,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// eslint-disable-next-line no-restricted-imports
 import { EventEmitter } from "events";
 
-export class ReEmitter {
-    private target: EventEmitter;
+import { ListenerMap, TypedEventEmitter } from "./models/typed-event-emitter";
 
-    constructor(target: EventEmitter) {
-        this.target = target;
-    }
+export class ReEmitter {
+    constructor(private readonly target: EventEmitter) {}
 
-    reEmit(source: EventEmitter, eventNames: string[]) {
+    public reEmit(source: EventEmitter, eventNames: string[]): void {
         for (const eventName of eventNames) {
             // We include the source as the last argument for event handlers which may need it,
             // such as read receipt listeners on the client class which won't have the context
@@ -48,3 +47,19 @@ export class ReEmitter {
         }
     }
 }
+
+export class TypedReEmitter<
+    Events extends string,
+    Arguments extends ListenerMap<Events>,
+> extends ReEmitter {
+    constructor(target: TypedEventEmitter<Events, Arguments>) {
+        super(target);
+    }
+
+    public reEmit<ReEmittedEvents extends string, T extends Events & ReEmittedEvents>(
+        source: TypedEventEmitter<ReEmittedEvents, any>,
+        eventNames: T[],
+    ): void {
+        super.reEmit(source, eventNames);
+    }
+}