feat: add icalendar file download support

cspell/custom-dict.txt

@@ -69,6 +69,7 @@ gunicorn
 hackathon
 heroui
 hsl
+ics
 igoat
 inlinehilite
 isanori

frontend/__tests__/e2e/pages/CalendarButton.spec.ts

@@ -0,0 +1,48 @@
+import fs from 'node:fs'
+import { mockHomeData } from '@e2e/data/mockHomeData'
+import { test, expect } from '@playwright/test'
+import slugify from 'utils/slugify'
+
+test.describe('Calendar Export Functionality', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.route('**/graphql/', async (route) => {
+      await route.fulfill({
+        status: 200,
+        json: mockHomeData,
+      })
+    })
+    await page.context().addCookies([
+      {
+        name: 'csrftoken',
+        value: 'abc123',
+        domain: 'localhost',
+        path: '/',
+      },
+    ])
+    await page.goto('/')
+  })
+
+  test('should download a valid ICS file when clicked', async ({ page }) => {
+    const calendarButton = page.getByRole('button', { name: 'Add Event 1 to Calendar' })
+    await expect(calendarButton).toBeVisible()
+
+    const downloadPromise = page.waitForEvent('download')
+
+    await calendarButton.click()
+
+    const download = await downloadPromise
+
+    expect(download.suggestedFilename()).toBe(`${slugify('Event 1')}.ics`)
+
+    const path = await download.path()
+    expect(path, 'Expected Playwright to provide a download path').toBeTruthy()
+    const content = fs.readFileSync(path, 'utf-8')
+
+    expect(content).toContain('BEGIN:VCALENDAR')
+    expect(content).toContain('VERSION:2.0')
+    expect(content).toContain('BEGIN:VEVENT')
+
+    expect(content).toContain('SUMMARY:')
+    expect(content).toContain('END:VCALENDAR')
+  })
+})

frontend/__tests__/e2e/pages/Home.spec.ts

@@ -100,9 +100,9 @@ test.describe('Home Page', () => {
     await expect(page.getByRole('heading', { name: 'Upcoming Events' })).toBeVisible({
       timeout: 10000,
     })
-    await expect(page.getByRole('button', { name: 'Event 1' })).toBeVisible()
+    await expect(page.getByRole('button', { name: 'Event 1', exact: true })).toBeVisible()
     await expect(page.getByText('Apr 5 — 6, 2025')).toBeVisible()
-    await page.getByRole('button', { name: 'Event 1' }).click()
+    await page.getByRole('button', { name: 'Event 1', exact: true }).click()
   })
 
   test('should have stats', async ({ page }) => {