test(gateway): 补充账号调度优化的单元测试

- 添加 GetAccountsLoadBatch 批量负载查询测试
- 添加 CleanupExpiredAccountSlots 过期槽位清理测试
- 添加 SelectAccountWithLoadAwareness 负载感知选择测试
- 测试覆盖降级行为、账号排除、错误处理等场景

backend/internal/repository/concurrency_cache_integration_test.go

@@ -274,6 +274,138 @@ func (s *ConcurrencyCacheSuite) TestGetUserConcurrency_Missing() {
 	require.Equal(s.T(), 0, cur)
 }
 
+func (s *ConcurrencyCacheSuite) TestGetAccountsLoadBatch() {
+	// Setup: Create accounts with different load states
+	account1 := int64(100)
+	account2 := int64(101)
+	account3 := int64(102)
+
+	// Account 1: 2/3 slots used, 1 waiting
+	ok, err := s.cache.AcquireAccountSlot(s.ctx, account1, 3, "req1")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+	ok, err = s.cache.AcquireAccountSlot(s.ctx, account1, 3, "req2")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+	ok, err = s.cache.IncrementAccountWaitCount(s.ctx, account1, 5)
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+
+	// Account 2: 1/2 slots used, 0 waiting
+	ok, err = s.cache.AcquireAccountSlot(s.ctx, account2, 2, "req3")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+
+	// Account 3: 0/1 slots used, 0 waiting (idle)
+
+	// Query batch load
+	accounts := []service.AccountWithConcurrency{
+		{ID: account1, MaxConcurrency: 3},
+		{ID: account2, MaxConcurrency: 2},
+		{ID: account3, MaxConcurrency: 1},
+	}
+
+	loadMap, err := s.cache.GetAccountsLoadBatch(s.ctx, accounts)
+	require.NoError(s.T(), err)
+	require.Len(s.T(), loadMap, 3)
+
+	// Verify account1: (2 + 1) / 3 = 100%
+	load1 := loadMap[account1]
+	require.NotNil(s.T(), load1)
+	require.Equal(s.T(), account1, load1.AccountID)
+	require.Equal(s.T(), 2, load1.CurrentConcurrency)
+	require.Equal(s.T(), 1, load1.WaitingCount)
+	require.Equal(s.T(), 100, load1.LoadRate)
+
+	// Verify account2: (1 + 0) / 2 = 50%
+	load2 := loadMap[account2]
+	require.NotNil(s.T(), load2)
+	require.Equal(s.T(), account2, load2.AccountID)
+	require.Equal(s.T(), 1, load2.CurrentConcurrency)
+	require.Equal(s.T(), 0, load2.WaitingCount)
+	require.Equal(s.T(), 50, load2.LoadRate)
+
+	// Verify account3: (0 + 0) / 1 = 0%
+	load3 := loadMap[account3]
+	require.NotNil(s.T(), load3)
+	require.Equal(s.T(), account3, load3.AccountID)
+	require.Equal(s.T(), 0, load3.CurrentConcurrency)
+	require.Equal(s.T(), 0, load3.WaitingCount)
+	require.Equal(s.T(), 0, load3.LoadRate)
+}
+
+func (s *ConcurrencyCacheSuite) TestGetAccountsLoadBatch_Empty() {
+	// Test with empty account list
+	loadMap, err := s.cache.GetAccountsLoadBatch(s.ctx, []service.AccountWithConcurrency{})
+	require.NoError(s.T(), err)
+	require.Empty(s.T(), loadMap)
+}
+
+func (s *ConcurrencyCacheSuite) TestCleanupExpiredAccountSlots() {
+	accountID := int64(200)
+	slotKey := fmt.Sprintf("%s%d", accountSlotKeyPrefix, accountID)
+
+	// Acquire 3 slots
+	ok, err := s.cache.AcquireAccountSlot(s.ctx, accountID, 5, "req1")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+	ok, err = s.cache.AcquireAccountSlot(s.ctx, accountID, 5, "req2")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+	ok, err = s.cache.AcquireAccountSlot(s.ctx, accountID, 5, "req3")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+
+	// Verify 3 slots exist
+	cur, err := s.cache.GetAccountConcurrency(s.ctx, accountID)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), 3, cur)
+
+	// Manually set old timestamps for req1 and req2 (simulate expired slots)
+	now := time.Now().Unix()
+	expiredTime := now - int64(testSlotTTL.Seconds()) - 10 // 10 seconds past TTL
+	err = s.rdb.ZAdd(s.ctx, slotKey, redis.Z{Score: float64(expiredTime), Member: "req1"}).Err()
+	require.NoError(s.T(), err)
+	err = s.rdb.ZAdd(s.ctx, slotKey, redis.Z{Score: float64(expiredTime), Member: "req2"}).Err()
+	require.NoError(s.T(), err)
+
+	// Run cleanup
+	err = s.cache.CleanupExpiredAccountSlots(s.ctx, accountID)
+	require.NoError(s.T(), err)
+
+	// Verify only 1 slot remains (req3)
+	cur, err = s.cache.GetAccountConcurrency(s.ctx, accountID)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), 1, cur)
+
+	// Verify req3 still exists
+	members, err := s.rdb.ZRange(s.ctx, slotKey, 0, -1).Result()
+	require.NoError(s.T(), err)
+	require.Len(s.T(), members, 1)
+	require.Equal(s.T(), "req3", members[0])
+}
+
+func (s *ConcurrencyCacheSuite) TestCleanupExpiredAccountSlots_NoExpired() {
+	accountID := int64(201)
+
+	// Acquire 2 fresh slots
+	ok, err := s.cache.AcquireAccountSlot(s.ctx, accountID, 5, "req1")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+	ok, err = s.cache.AcquireAccountSlot(s.ctx, accountID, 5, "req2")
+	require.NoError(s.T(), err)
+	require.True(s.T(), ok)
+
+	// Run cleanup (should not remove anything)
+	err = s.cache.CleanupExpiredAccountSlots(s.ctx, accountID)
+	require.NoError(s.T(), err)
+
+	// Verify both slots still exist
+	cur, err := s.cache.GetAccountConcurrency(s.ctx, accountID)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), 2, cur)
+}
+
 func TestConcurrencyCacheSuite(t *testing.T) {
 	suite.Run(t, new(ConcurrencyCacheSuite))
 }