fix: coalesce concurrent notification count reads

src/modules/notifications/store/notifications.test.mjs

@@ -0,0 +1,49 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { readFileSync } from 'node:fs'
+import ts from 'typescript'
+import { computed, ref } from 'vue'
+
+function setup() {
+  const requests = []
+  const source = readFileSync(new URL('./notifications.ts', import.meta.url), 'utf8').replace(/^import [^\r\n]*\r?\n/gm, '').replace('export const', 'const')
+  const code = ts.transpileModule(source, { compilerOptions: { target: ts.ScriptTarget.ES2022 } }).outputText
+  const store = new Function('computed', 'ref', 'defineStore', 'getMyUnreadNotificationCount', code + '\nreturn useNotificationsStore()')(computed, ref, (_id, factory) => factory, () => new Promise((resolve, reject) => requests.push({ resolve, reject })))
+  return { store, requests }
+}
+
+test('shell and page concurrent reads share one pending request', async () => {
+  const { store, requests } = setup()
+  const a = store.refreshUnreadCount(), b = store.refreshUnreadCount()
+  assert.equal(requests.length, 1)
+  requests[0].resolve(5)
+  await Promise.all([a, b])
+  assert.equal(store.unreadCount.value, 5)
+  assert.equal(store.loading.value, false)
+})
+
+test('post-mutation refresh reads again after a pending pre-mutation read', async () => {
+  const { store, requests } = setup()
+  const a = store.refreshUnreadCount(), b = store.refreshUnreadCount(true)
+  assert.equal(requests.length, 1)
+  requests[0].resolve(5)
+  await a
+  await Promise.resolve()
+  assert.equal(requests.length, 2)
+  requests[1].resolve(0)
+  await b
+  assert.equal(store.unreadCount.value, 0)
+})
+
+test('failed request releases the pending guard for retry', async () => {
+  const { store, requests } = setup()
+  const a = store.refreshUnreadCount()
+  requests[0].reject(new Error('network'))
+  await a
+  const b = store.refreshUnreadCount()
+  assert.equal(requests.length, 2)
+  requests[1].resolve(2)
+  await b
+  assert.equal(store.unreadCount.value, 2)
+  assert.equal(store.errorMessage.value, '')
+})