[EC-598] feat: add basic test-case for messenger

apps/browser/src/content/webauthn/messaging/messenger.spec.ts

@@ -0,0 +1,83 @@
+import { Subject } from "rxjs";
+
+import { Utils } from "@bitwarden/common/misc/utils";
+
+import { Message } from "./message";
+import { Channel, MessageWithMetadata, Messenger } from "./messenger";
+
+describe("Messenger", () => {
+  let messengerA: Messenger;
+  let messengerB: Messenger;
+  let handlerA: TestMessageHandler;
+  let handlerB: TestMessageHandler;
+
+  beforeEach(() => {
+    const channelPair = new TestChannelPair();
+    messengerA = new Messenger(channelPair.channelA);
+    messengerB = new Messenger(channelPair.channelB);
+
+    handlerA = new TestMessageHandler();
+    handlerB = new TestMessageHandler();
+    messengerA.addHandler(handlerA.handler);
+    messengerB.addHandler(handlerB.handler);
+  });
+
+  it("should deliver message to B when sending request to A", () => {
+    const message = createMessage();
+    messengerA.request(message);
+
+    const received = handlerB.recieve();
+
+    expect(received.length).toBe(1);
+    expect(received[0].message).toMatchObject(message);
+  });
+});
+
+type TestMessage = Message & { testId: string };
+
+function createMessage(): TestMessage {
+  return { testId: Utils.newGuid(), type: "TestMessage" } as any;
+}
+
+class TestChannelPair {
+  readonly channelA: Channel;
+  readonly channelB: Channel;
+
+  constructor() {
+    const subjectA = new Subject<MessageWithMetadata>();
+    const subjectB = new Subject<MessageWithMetadata>();
+
+    this.channelA = {
+      messages$: subjectA,
+      postMessage: (message) => subjectB.next(message),
+    };
+
+    this.channelB = {
+      messages$: subjectB,
+      postMessage: (message) => subjectB.next(message),
+    };
+  }
+}
+
+class TestMessageHandler {
+  readonly handler: (message: TestMessage) => Promise<Message | undefined>;
+
+  private recievedMessages: { message: TestMessage; respond: (response: TestMessage) => void }[] =
+    [];
+
+  constructor() {
+    this.handler = (message) =>
+      new Promise((resolve, reject) => {
+        this.recievedMessages.push({
+          message,
+          respond: (response) => resolve(response),
+        });
+      });
+  }
+
+  recieve() {
+    const received = this.recievedMessages;
+    this.recievedMessages = [];
+    return received;
+  }
+}

apps/browser/src/content/webauthn/messaging/messenger.ts

@@ -4,13 +4,13 @@ import { Message } from "./message";
 
 type PostMessageFunction = (message: MessageWithMetadata) => void;
 
-type Channel = {
+export type Channel = {
   messages$: Observable<MessageWithMetadata>;
   postMessage: PostMessageFunction;
 };
 
-type Metadata = { requestId: string };
+export type Metadata = { requestId: string };
-type MessageWithMetadata = Message & { metadata: Metadata };
+export type MessageWithMetadata = Message & { metadata: Metadata };
 
 // TODO: This class probably duplicates functionality but I'm not especially familiar with
 // the inner workings of the browser extension yet.
@@ -32,7 +32,7 @@ export class Messenger {
     });
   }
 
-  private constructor(private channel: Channel) {}
+  constructor(private channel: Channel) {}
 
   request(request: Message): Promise<Message> {
     const requestId = Date.now().toString();