Fair point. Perhaps also worth noting that an "end-to-end" test has been performed by the US exactly once.
I find it somewhat incredible from a pure engineering point of view that Trinity worked in the first test and that both Little Boy (Test #2) and Fat Man (Test #3) also worked.
"Frigate Bird was the only US test of an operational ballistic missile with a live warhead."
https://nuclearweaponarchive.org/Usa/Tests/Dominic.html#Frig...