tests/test_generics.rs

extern crate syn;
use syn::*;

#[macro_use]
extern crate quote;

#[test]
fn test_split_for_impl() {
    // <'a, 'b: 'a, #[may_dangle] T: 'a = ()> where T: Debug
    let generics = Generics {
        lifetimes: vec![
            LifetimeDef {
                attrs: Vec::new(),
                lifetime: Lifetime::new("'a"),
                bounds: Vec::new(),
            },
            LifetimeDef {
                attrs: Vec::new(),
                lifetime: Lifetime::new("'b"),
                bounds: vec![
                    Lifetime::new("'a"),
                ],
            },
        ],
        ty_params: vec![
            TyParam {
                attrs: vec![
                    Attribute {
                        style: AttrStyle::Outer,
                        value: MetaItem::Word("may_dangle".into()),
                        is_sugared_doc: false,
                    },
                ],
                ident: Ident::new("T"),
                bounds: vec![
                    TyParamBound::Region(Lifetime::new("'a")),
                ],
                default: Some(Ty::Tup(Vec::new())),
            },
        ],
        where_clause: WhereClause {
            predicates: vec![
                WherePredicate::BoundPredicate(WhereBoundPredicate {
                    bound_lifetimes: Vec::new(),
                    bounded_ty: Ty::Path(None, "T".into()),
                    bounds: vec![
                        TyParamBound::Trait(
                            PolyTraitRef {
                                bound_lifetimes: Vec::new(),
                                trait_ref: "Debug".into(),
                            },
                            TraitBoundModifier::None,
                        ),
                    ],
                }),
            ],
        },
    };

    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();

    let tokens = quote! {
        impl #impl_generics MyTrait for Test #ty_generics #where_clause {}
    };

    let expected = concat!(
        "impl < 'a , 'b : 'a , # [ may_dangle ] T : 'a > ",
        "MyTrait for Test < 'a , 'b , T > ",
        "where T : Debug { }"
    );

    assert_eq!(expected, tokens.to_string());
}