tududi/frontend/__tests__/components/Login.test.tsx

import React from 'react';
import { render, screen, fireEvent, waitFor, act } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { BrowserRouter } from 'react-router-dom';
import Login from '../../components/Login';

// Mock fetch
global.fetch = jest.fn();

const renderLogin = () => {
  return render(
    <BrowserRouter>
      <Login />
    </BrowserRouter>
  );
};

describe('Login Component', () => {
  beforeEach(() => {
    (fetch as jest.Mock).mockClear();
  });

  it('renders login form', () => {
    renderLogin();
    
    expect(screen.getByLabelText(/email/i)).toBeInTheDocument();
    expect(screen.getByLabelText(/password/i)).toBeInTheDocument();
    expect(screen.getByRole('button', { name: /login/i })).toBeInTheDocument();
  });

  it('handles form submission with valid credentials', async () => {
    const user = userEvent.setup();
    (fetch as jest.Mock).mockResolvedValueOnce({
      ok: true,
      json: async () => ({ success: true, user: { email: 'test@example.com' } })
    });

    renderLogin();

    await act(async () => {
      await user.type(screen.getByLabelText(/email/i), 'test@example.com');
      await user.type(screen.getByLabelText(/password/i), 'password123');
    });

    await act(async () => {
      await user.click(screen.getByRole('button', { name: /login/i }));
    });

    await waitFor(() => {
      expect(fetch).toHaveBeenCalledWith('/api/login', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        credentials: 'include',
        body: JSON.stringify({
          email: 'test@example.com',
          password: 'password123'
        })
      });
    });
  });

  it('displays error message on failed login', async () => {
    const user = userEvent.setup();
    (fetch as jest.Mock).mockResolvedValueOnce({
      ok: false,
      json: async () => ({ error: 'Invalid credentials' })
    });

    renderLogin();

    await act(async () => {
      await user.type(screen.getByLabelText(/email/i), 'test@example.com');
      await user.type(screen.getByLabelText(/password/i), 'wrongpassword');
    });

    await act(async () => {
      await user.click(screen.getByRole('button', { name: /login/i }));
    });

    await waitFor(() => {
      expect(screen.getByText(/an error occurred/i)).toBeInTheDocument();
    });
  });

  it('validates required fields', async () => {
    const user = userEvent.setup();
    renderLogin();

    await act(async () => {
      await user.click(screen.getByRole('button', { name: /login/i }));
    });

    // Should not make API call with empty fields
    expect(fetch).not.toHaveBeenCalled();
  });
});