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use darling::FromTypeParam;
use syn::{parse_quote, DeriveInput, GenericParam, Ident, TypeParam};
#[derive(FromTypeParam)]
#[darling(attributes(lorem), from_ident)]
struct Lorem {
ident: Ident,
bounds: Vec<syn::TypeParamBound>,
foo: bool,
bar: Option<String>,
}
impl From<Ident> for Lorem {
fn from(ident: Ident) -> Self {
Lorem {
ident,
foo: false,
bar: None,
bounds: Default::default(),
}
}
}
fn extract_type(param: &GenericParam) -> &TypeParam {
match *param {
GenericParam::Type(ref ty) => ty,
_ => unreachable!("Not a type param"),
}
}
#[test]
#[allow(clippy::bool_assert_comparison)]
fn expand_many() {
let di: DeriveInput = parse_quote! {
struct Baz<
#[lorem(foo)] T,
#[lorem(bar = "x")] U: Eq + ?Sized
>(T, U);
};
let params = di.generics.params;
{
let ty = extract_type(¶ms[0]);
let lorem = Lorem::from_type_param(ty).unwrap();
assert_eq!(lorem.ident, "T");
assert_eq!(lorem.foo, true);
assert_eq!(lorem.bar, None);
}
{
let ty = extract_type(¶ms[1]);
let lorem = Lorem::from_type_param(ty).unwrap();
assert_eq!(lorem.ident, "U");
assert_eq!(lorem.foo, false);
assert_eq!(lorem.bar, Some("x".to_string()));
assert_eq!(lorem.bounds.len(), 2);
}
}