enum-derive-2018 3.0.2

This crate provides macros for deriving additional functionality for enums.
Documentation 
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// Copyright (c) 2015 macro-attr contributors.
// Copyright (c) 2020 Warlock <internalmike@gmail.com>.
//
// Licensed under the MIT license (see LICENSE or <http://opensource.org
// /licenses/MIT>) or the Apache License, Version 2.0 (see LICENSE of
// <http://www.apache.org/licenses/LICENSE-2.0>), at your option. All
// files in the project carrying such notice may not be copied, modified,
// or distributed except according to those terms.

#![deny(warnings)]
#![allow(clippy::needless_collect)]

use enum_derive_2018::{IterVariants, IterVariantNames};
use macro_attr_2018::macro_attr;

macro_attr! {
    #[derive(Debug, PartialEq, IterVariants!(GetVariants), IterVariantNames!(GetVariantNames))]
    pub enum Get {
        Up,
        /// And
        Down,
        /** And */
        AllAround
    }
}

macro_attr! {
    #[derive(IterVariants!(NadaVariants), IterVariantNames!(NadaVariantNames))]
    enum Nada {}
}

#[cfg(test)]
fn test_size<I, T: Iterator<Item=I> + ExactSizeIterator>(mut iter: T, size: usize) {
    for i in 0..size {
        assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
        assert!(iter.next().is_some());
    }

    assert_eq!(iter.size_hint(), (0, Some(0)));
    assert!(iter.next().is_none());
}

#[test]
fn test_enum_iterator() {
    let vs: Vec<_> = Get::iter_variant_names().zip(Get::iter_variants()).collect();
    assert_eq!(&*vs, &[("Up", Get::Up), ("Down", Get::Down), ("AllAround", Get::AllAround)]);

    test_size(Nada::iter_variants(), 0);
    test_size(Nada::iter_variant_names(), 0);
    test_size(Get::iter_variants(), 3);
    test_size(Get::iter_variant_names(), 3);

    assert_eq!(Nada::iter_variants().collect::<Vec<_>>().len(), 0);
    assert_eq!(Nada::iter_variant_names().collect::<Vec<_>>().len(), 0);
}