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use darling::{ast, FromDeriveInput, FromVariant};
#[derive(Debug, FromDeriveInput)]
#[darling(attributes(from_variants), supports(enum_any))]
pub struct Container {
// The second type parameter can be anything that implements FromField, since
// FromDeriveInput will produce an error if given a struct.
data: ast::Data<Variant, ()>,
}
#[derive(Default, Debug, FromVariant)]
#[darling(default, attributes(from_variants), supports(newtype, unit))]
pub struct Variant {
into: Option<bool>,
skip: Option<bool>,
}
#[derive(Debug, FromDeriveInput)]
#[darling(attributes(from_struct), supports(struct_named))]
pub struct StructContainer {
// The second type parameter can be anything that implements FromVariant, since
// FromDeriveInput will produce an error if given an enum.
data: ast::Data<(), syn::Field>,
}
mod source {
use syn::{parse_quote, DeriveInput};
pub fn newtype_enum() -> DeriveInput {
parse_quote! {
enum Hello {
World(bool),
String(String),
}
}
}
pub fn named_field_enum() -> DeriveInput {
parse_quote! {
enum Hello {
Foo(u16),
World {
name: String
},
}
}
}
pub fn empty_enum() -> DeriveInput {
parse_quote! {
enum Hello {}
}
}
pub fn named_struct() -> DeriveInput {
parse_quote! {
struct Hello {
world: bool,
}
}
}
pub fn tuple_struct() -> DeriveInput {
parse_quote! { struct Hello(String, bool); }
}
}
#[test]
fn enum_newtype_or_unit() {
// Should pass
let container = Container::from_derive_input(&source::newtype_enum()).unwrap();
assert!(container.data.is_enum());
// Should error
Container::from_derive_input(&source::named_field_enum()).unwrap_err();
Container::from_derive_input(&source::named_struct()).unwrap_err();
}
#[test]
fn struct_named() {
// Should pass
let container = StructContainer::from_derive_input(&source::named_struct()).unwrap();
assert!(container.data.is_struct());
// Should fail
StructContainer::from_derive_input(&source::tuple_struct()).unwrap_err();
StructContainer::from_derive_input(&source::named_field_enum()).unwrap_err();
StructContainer::from_derive_input(&source::newtype_enum()).unwrap_err();
StructContainer::from_derive_input(&source::empty_enum()).unwrap_err();
}