I had to test, did not think this would work for the value 0 - it does

This would fail given the data:

find_smallest_int(&[2000, 3000, 4000])

Since 1000 would be returned, but would not originate from the array.

I like your solution, but returning 0 hence indicating 0 to be the smallest number would be a an error IMHO.

I really like this solution (as I also commented). I did not like the fact that the kata did not take into consideration the empty array, returning 0 would not be correct behaviour.

I like this solution alot, I thought some thing like this was possible, but my Rust-foo is not strong enough and I have a hard time navigating the documentation to dig up the idiomatic Rust examples

Very elegant, I like the use of the Rust idiom