refactor stack. Add details to example tests.

components/__tests__/index.spec.tsx

@@ -0,0 +1,30 @@
+import React from 'react';
+import { fireEvent, render, screen } from '@testing-library/react-native';
+import { NavigationContainer } from '@react-navigation/native';
+import { createStackNavigator } from '@react-navigation/stack';
+import TTNavStack from '../TTNavStack';
+
+jest.mock('expo-file-system', () => require('./__mocks__/expo-file-system'));
+
+const Stack = createStackNavigator();
+
+describe('Navigation', () => {
+  beforeEach(() => {
+    // Reset the navigation state before each test
+    jest.clearAllMocks();
+  });
+
+  it('Navigates to ConversationThread on language selection', async () => {
+    render(<TTNavStack />);
+    const languageSelectionText = await screen.findByText("Language Selection");
+    fireEvent.press(languageSelectionText);
+    expect(await screen.findByText("Conversation Thread")).toBeOnTheScreen();
+  });
+
+  it('Navigates to Settings on settings selection', async () => {
+    render(<TTNavStack />);
+    const settingsButton = await screen.findByText("Settings");
+    fireEvent.press(settingsButton);
+    expect(await screen.findByText("Settings")).toBeOnTheScreen();
+  });
+});