cache := c.(*lruCache[uint64])

	assert.Equal(t, cache.store.Len(), 0)
	assert.Equal(t, cache.indexLength(), 0)

	// adding the entry populates the indexes
	c.Add(firstEntry.Key(), firstEntry, req, res)

	assert.Equal(t, cache.store.Len(), 1)
	assert.Equal(t, cache.indexLength(), 2)
	assert.Equal(t, cache.configIndexSnapshot(), map[ConfigHash]sets.Set[uint64]{

	for i, ik := range iKeys {
		v, ok := l.store.Get(ik)
		if !ok {
			continue
		}

		res[i] = v.value
	}
	return res
}

func (l *lruCache[K]) indexLength() int {
	l.mu.RLock()
	defer l.mu.RUnlock()
	return len(l.configIndex)
}

func (l *lruCache[K]) configIndexSnapshot() map[ConfigHash]sets.Set[K] {
	l.mu.RLock()
	defer l.mu.RUnlock()