Well if there are small indication that they're good friend they would at least gave out small hint and sign here and there, such as a tap to the hand(elbow) or a whisper to the ear. If not then you'll move along knowing that it didn't work and you need to try again
. Remember to proceed like that didn't faze you.The bigger the better, the best friends test dosen't necessary mean it's limit to a two set of woman, it's just a way to introduce yourself and acknowledge your presence. Just proceed them normality.
Good luck.
_Saiko