How do I study BLE transmission efficiency?

[vishesh-varma]

Hi! This NimBLE library is very high-level wrapper of the BLE implementation. I haven't seen much functions available to see how efficient my communication is. My device is going to be surrounded by an aluminum foil, and I wanted to know how much that will ruin the transmission rates.
I don't think I can gather reliable and statistically accurate data just based off of RSSI.
What kind of tests can I perform to get a gist of how well am I able to transmit data?