#[cfg(feature = "use_core")]
extern crate core;
#[macro_use]
extern crate derivative;
use std::collections::BTreeMap;
use std::iter::Iterator;
#[derive(Derivative)]
#[derive(Ord, PartialOrd)]
#[derivative(Eq, Hash, Debug, PartialEq)]
struct Zst;
#[test]
fn main() {
const N: usize = 8;
for len in 0..N {
let mut tester = BTreeMap::new();
assert_eq!(tester.len(), 0);
for _ in 0..len {
tester.insert(Zst, ());
}
assert_eq!(tester.len(), if len == 0 { 0 } else { 1 });
assert_eq!(tester.iter().count(), if len == 0 { 0 } else { 1 });
assert_eq!(tester.get(&Zst).is_some(), len > 0);
tester.clear();
}
}