fix unit tests. add conversation model and add unit tests to it.

app/lib/__test__/conversation.test.tsx

@@ -0,0 +1,32 @@
+// conversation.test.ts
+
+import { Translator } from '@/app/i18n/api';
+import { Conversation, Message, Speaker } from '@/app/lib/conversation';
+import { describe, beforeEach, it, expect, test } from '@jest/globals';
+
+describe('Conversation', () => {
+  let conversation: Conversation;
+
+  beforeEach(() => {
+    const translator = new Translator("en", "sp");
+    const s1: Speaker = { language: "en", id: "s1" };
+    const s2: Speaker = { id: "s2", language: "sp" }
+    conversation = new Conversation(translator, s1, s2);
+  });
+
+  it('should add a message to the conversation', () => {
+    conversation.addMessage({ id: "s1", language: "en" }, "Hello");
+    expect(true).toEqual(false);
+    expect(conversation.length).toBe(1);
+    expect(conversation[0].speaker.id).toEqual("s1");
+    expect(conversation[0].text).toEqual("hello");
+  });
+
+  it('should translate the last message in the conversation', async () => {
+
+    conversation.addMessage({ id: "s1", language: "en" }, "Hello");
+
+    await conversation.translateLast();
+    expect(conversation[conversation.length - 1].translation).toEqual("Hollla");
+  });
+});