test(Export): add UI tests

Author: Bogay

gdnative-derive/src/export.rs

@@ -1,14 +1,19 @@
-use proc_macro2::TokenStream as TokenStream2;
+use proc_macro2::{Span, TokenStream as TokenStream2};
+use syn::spanned::Spanned;
 use syn::{DeriveInput, Fields};
 
+fn err_only_supports_fieldless_enums(span: Span) -> syn::Error {
+    syn::Error::new(span, "#[derive(Export)] only supports fieldless enums")
+}
+
 pub(crate) fn derive_export(input: &DeriveInput) -> syn::Result<TokenStream2> {
     let derived_enum = match &input.data {
         syn::Data::Enum(data) => data,
-        _ => {
-            return Err(syn::Error::new(
-                input.ident.span(),
-                "#[derive(Export)] only supports fieldless enums",
-            ))
+        syn::Data::Struct(data) => {
+            return Err(err_only_supports_fieldless_enums(data.struct_token.span()));
+        }
+        syn::Data::Union(data) => {
+            return Err(err_only_supports_fieldless_enums(data.union_token.span()));
         }
     };
 
@@ -20,14 +25,8 @@ fn impl_export(enum_ty: &syn::Ident, data: &syn::DataEnum) -> syn::Result<TokenS
     let err = data
         .variants
         .iter()
-        .filter_map(|variant| {
-            (!matches!(variant.fields, Fields::Unit)).then(|| {
-                syn::Error::new(
-                    variant.ident.span(),
-                    "#[derive(Export)] only supports fieldless enums",
-                )
-            })
-        })
+        .filter(|variant| !matches!(variant.fields, Fields::Unit))
+        .map(|variant| err_only_supports_fieldless_enums(variant.ident.span()))
         .reduce(|mut acc, err| {
             acc.combine(err);
             acc

gdnative/tests/ui.rs

@@ -42,7 +42,10 @@ fn ui_tests() {
     t.compile_fail("tests/ui/from_variant_fail_09.rs");
 
     // Export
+    t.pass("tests/ui/export_pass.rs");
     t.compile_fail("tests/ui/export_fail_01.rs");
+    t.compile_fail("tests/ui/export_fail_02.rs");
+    t.compile_fail("tests/ui/export_fail_03.rs");
 }
 
 // FIXME(rust/issues/54725): Full path spans are only available on nightly as of now

gdnative/tests/ui/export_fail_02.rs

@@ -0,0 +1,8 @@
+use gdnative::prelude::*;
+
+#[derive(Export, ToVariant)]
+pub struct Foo {
+    bar: i32,
+}
+
+fn main() {}

gdnative/tests/ui/export_fail_02.stderr

@@ -0,0 +1,5 @@
+error: #[derive(Export)] only supports fieldless enums
+ --> tests/ui/export_fail_02.rs:4:5
+  |
+4 | pub struct Foo {
+  |     ^^^^^^

gdnative/tests/ui/export_fail_03.rs

@@ -0,0 +1,8 @@
+use gdnative::prelude::*;
+
+#[derive(Export, ToVariant)]
+pub union Foo {
+    bar: i32,
+}
+
+fn main() {}

gdnative/tests/ui/export_fail_03.stderr

@@ -0,0 +1,11 @@
+error: #[derive(Export)] only supports fieldless enums
+ --> tests/ui/export_fail_03.rs:4:5
+  |
+4 | pub union Foo {
+  |     ^^^^^
+
+error: Variant conversion derive macro does not work on unions.
+ --> tests/ui/export_fail_03.rs:4:1
+  |
+4 | pub union Foo {
+  | ^^^

gdnative/tests/ui/export_pass.rs

@@ -0,0 +1,11 @@
+use gdnative::prelude::*;
+
+#[derive(Export, ToVariant, Clone, Copy)]
+#[variant(enum = "repr")]
+#[repr(i32)]
+pub enum Foo {
+    Bar,
+    Baz,
+}
+
+fn main() {}