Added tests, shift 'delete'. Fixed overnight shifts, sync, error handling.

frontend/src/db.test.js

@@ -0,0 +1,49 @@
+import { describe, it, expect, beforeEach } from 'vitest'
+import { db, getLastSync, setLastSync, getSession, saveSession, clearSession } from './db.js'
+
+beforeEach(async () => {
+  await Promise.all(db.tables.map(t => t.clear()))
+})
+
+describe('db schema', () => {
+  it('has expected tables', () => {
+    const names = db.tables.map(t => t.name).sort()
+    expect(names).toEqual([
+      'attendees', 'departments', 'event', 'meta',
+      'outbox', 'session', 'shifts', 'volunteer_shifts', 'volunteers',
+    ])
+  })
+})
+
+describe('session', () => {
+  it('returns undefined when no session', async () => {
+    const s = await getSession()
+    expect(s).toBeUndefined()
+  })
+
+  it('saves and retrieves session', async () => {
+    await saveSession('tok123', { id: 1, username: 'admin', role: 'admin' })
+    const s = await getSession()
+    expect(s.token).toBe('tok123')
+    expect(s.user.username).toBe('admin')
+  })
+
+  it('clears session and meta', async () => {
+    await saveSession('tok123', { id: 1 })
+    await setLastSync('2026-01-01T00:00:00Z')
+    await clearSession()
+    expect(await getSession()).toBeUndefined()
+    expect(await getLastSync()).toBe('')
+  })
+})
+
+describe('lastSync', () => {
+  it('returns empty string when unset', async () => {
+    expect(await getLastSync()).toBe('')
+  })
+
+  it('roundtrips a timestamp', async () => {
+    await setLastSync('2026-03-01T12:00:00Z')
+    expect(await getLastSync()).toBe('2026-03-01T12:00:00Z')
+  })
+})