test: improve test coverage and API integration

- Change assertion to check for zero logs instead of one in `TestSyncModeForTopicNotification`

Signed-off-by: Bo-Yi Wu <[email protected]>

router/server_test.go

@@ -621,7 +621,7 @@ func TestSyncModeForTopicNotification(t *testing.T) {
 
 	count, logs := handleNotification(ctx, cfg, req, q)
 	assert.Equal(t, 2, count)
-	assert.Equal(t, 1, len(logs))
+	assert.Equal(t, 0, len(logs))
 }
 
 func TestSyncModeForDeviceGroupNotification(t *testing.T) {