todo_tests

Надо написать тесты для проекта. Вот примерный план:

**Backend:**

4.  **WebSocket Event Tests (using Flask-SocketIO test client):**
    *   Test the `join` event (`joinChatRoom`): Simulate a client joining, verify server-side state (e.g., user added to room), and check if `user_joined` (`socket.on("user_joined")`) is broadcast correctly.
    *   Test the `send_message` event (`sendMessage`): Simulate sending a message, verify it's saved to the database (`ChatMessage`), and check if it's broadcast to the correct room.
    *   Test the `update_username` event (`updateUsername`): Simulate a username update, verify the change in the database (`User`), and check for any related broadcasts.
    *   Test disconnection handling: Simulate a client disconnecting and verify that `user_left` (`socket.on("user_left")`) is broadcast.

**Frontend (JavaScript - potentially using Jest, Cypress, or similar in tests or a dedicated frontend test folder):**

1.  **WebSocket Connection & Chat Join:**
    *   Verify that the socket connects successfully on page load (`socket.on('connect')`).
    *   Ensure the `join` event is emitted with the correct `chatId` when the chat page loads (`joinChatRoom`).
2.  **Message Handling:**
    *   Test `loadPreviousMessages` to ensure it fetches and displays messages from the API correctly.
    *   Test `sendMessage`: Mock the socket emit, verify the input is cleared, and the correct data is sent.
    *   Test receiving messages: Mock incoming `message` events and verify they are added to the chat display (`addMessage`).
    *   Test receiving system messages (`user_joined`, `user_left`) and verify they are displayed correctly (`addMessage`).
3.  **UI Interaction:**
    *   Test clicking the send button triggers `sendMessage`.
    *   Test pressing Enter in the message input triggers `sendMessage`.
    *   Test the username update functionality (`updateUsername`).

Consider starting with unit tests for backend logic (models, helpers) and then adding integration tests for API endpoints and WebSocket events. For the frontend, component tests or end-to-end tests using a tool like Cypress can cover user interactions and WebSocket communication effectively.

Надо написать CI/CD pipeline для автоматизации тестирования и деплоя. Добавить pre-commit который будет форматировать/линтить код