fix(cookieStore): do not crash request handling when localStorage quota is exceeded

src/core/utils/cookieStore.test.ts

@@ -0,0 +1,65 @@
+// @vitest-environment node
+import { afterAll, afterEach, beforeAll, expect, it, vi } from 'vitest'
+import { cookieStore } from './cookieStore'
+
+const url = 'https://example.com'
+
+function createFakeLocalStorage(): Storage {
+  const store = new Map<string, string>()
+  return {
+    get length() {
+      return store.size
+    },
+    getItem: (key) => (store.has(key) ? store.get(key)! : null),
+    setItem: (key, value) => void store.set(key, String(value)),
+    removeItem: (key) => void store.delete(key),
+    clear: () => store.clear(),
+    key: (index) => Array.from(store.keys())[index] ?? null,
+  }
+}
+
+beforeAll(() => {
+  Reflect.set(globalThis, 'localStorage', createFakeLocalStorage())
+})
+
+afterAll(() => {
+  Reflect.deleteProperty(globalThis, 'localStorage')
+})
+
+afterEach(() => {
+  vi.restoreAllMocks()
+  localStorage.clear()
+})
+
+it('does not crash request handling when localStorage quota is exceeded', async () => {
+  const quotaError = new DOMException(
+    'The quota has been exceeded.',
+    'QuotaExceededError',
+  )
+  vi.spyOn(localStorage, 'setItem').mockImplementation(() => {
+    throw quotaError
+  })
+  const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {})
+
+  // Persisting the cookie fails because the storage quota is exceeded,
+  // but that must not throw and crash the request handling pipeline.
+  await expect(
+    cookieStore.setCookie('name=value', url),
+  ).resolves.toBeUndefined()
+
+  // The cookie must remain available in-memory for the current session.
+  expect(
+    cookieStore.getCookies(url).map((cookie) => `${cookie.key}=${cookie.value}`),
+  ).toEqual(['name=value'])
+
+  // A warning must be emitted so the failure is not silent.
+  expect(warnSpy).toHaveBeenCalledTimes(1)
+})
+
+it('persists cookies to localStorage when the quota is available', async () => {
+  await expect(
+    cookieStore.setCookie('token=abc', url),
+  ).resolves.toBeUndefined()
+
+  expect(localStorage.getItem('__msw-cookie-store__')).toContain('token')
+})

src/core/utils/cookieStore.ts

@@ -88,7 +88,18 @@ class CookieStore {
       }
     }
 
-    localStorage.setItem(this.#storageKey, JSON.stringify(data))
+    try {
+      localStorage.setItem(this.#storageKey, JSON.stringify(data))
+    } catch (error) {
+      // Persisting cookies to `localStorage` can fail (e.g. with a
+      // `QuotaExceededError` when the storage is full). Treat persistence as
+      // best-effort: the cookies remain available in-memory for the current
+      // session, and the failure must not crash the request handling pipeline.
+      console.warn(
+        '[MSW] Failed to persist cookies to "localStorage". Cookies will still work for the current session but will not survive a page reload. This is likely because the storage quota has been exceeded.',
+        error,
+      )
+    }
   }
 }