test(05-04): add failing tests for calendar widget

- Three test cases: event rendering with color dots, no-events empty state, no-sources empty state
- Mocks calendar-api and next-intl following existing test patterns

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/components/dashboard/widgets/calendar-widget.test.tsx

@@ -0,0 +1,120 @@
+import { cleanup, render, screen, waitFor } from '@testing-library/react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+// Mock next-intl
+vi.mock('next-intl', () => ({
+  useTranslations: (ns: string) => (key: string) => {
+    const map: Record<string, Record<string, string>> = {
+      widgets: {
+        'calendar.name': 'Calendar',
+        'calendar.description': 'Upcoming events',
+        'calendar.emptyNoSources': 'No calendar sources configured',
+        'calendar.emptyNoEvents': 'No upcoming events',
+        'calendar.loading': 'Loading...',
+      },
+    };
+    return map[ns]?.[key] ?? key;
+  },
+}));
+
+// Mock calendar-api
+const mockFetchEvents = vi.fn();
+const mockFetchSources = vi.fn();
+vi.mock('@/lib/calendar-api', () => ({
+  fetchEvents: (...args: unknown[]) => mockFetchEvents(...args),
+  fetchSources: (...args: unknown[]) => mockFetchSources(...args),
+}));
+
+afterEach(() => {
+  cleanup();
+  vi.restoreAllMocks();
+});
+
+describe('CalendarWidget', () => {
+  beforeEach(() => {
+    // Default: sources exist so we get past the source check
+    mockFetchSources.mockResolvedValue([
+      { id: 's1', name: 'Work', type: 'caldav', isVisible: true, color: '#ff0000' },
+    ]);
+  });
+
+  it('renders event titles, times, and source color dots for two events', async () => {
+    mockFetchEvents.mockResolvedValue([
+      {
+        id: 'e1',
+        sourceId: 's1',
+        title: 'Team Meeting',
+        start: '2026-06-24T10:00:00Z',
+        end: '2026-06-24T11:00:00Z',
+        allDay: false,
+        color: '#ff0000',
+      },
+      {
+        id: 'e2',
+        sourceId: 's1',
+        title: 'Lunch Break',
+        start: '2026-06-24T12:00:00Z',
+        end: '2026-06-24T13:00:00Z',
+        allDay: false,
+        color: '#00ff00',
+      },
+    ]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(
+      <CalendarWidget
+        instanceId="cal-1"
+        config={{}}
+        isEditMode={false}
+      />,
+    );
+
+    // Wait for events to load
+    await waitFor(() => {
+      expect(screen.getByText('Team Meeting')).toBeInTheDocument();
+    });
+
+    expect(screen.getByText('Lunch Break')).toBeInTheDocument();
+
+    // Source color dots should be rendered (8px circles)
+    const colorDots = screen.getAllByTestId('event-color-dot');
+    expect(colorDots).toHaveLength(2);
+  });
+
+  it('renders no-events message when sources exist but no events returned', async () => {
+    mockFetchEvents.mockResolvedValue([]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(
+      <CalendarWidget
+        instanceId="cal-2"
+        config={{}}
+        isEditMode={false}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText('No upcoming events')).toBeInTheDocument();
+    });
+  });
+
+  it('renders no-sources message when no sources configured', async () => {
+    mockFetchSources.mockResolvedValue([]);
+    mockFetchEvents.mockResolvedValue([]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(
+      <CalendarWidget
+        instanceId="cal-3"
+        config={{}}
+        isEditMode={false}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(
+        screen.getByText('No calendar sources configured'),
+      ).toBeInTheDocument();
+    });
+  });
+});