Add tests to util::IdentList

core/src/util/ident_list.rs

@@ -52,10 +52,50 @@ impl FromMeta for IdentList {
             if let NestedMeta::Meta(Meta::Word(ref ident)) = *nmi {
                 idents.push(ident.clone());
             } else {
-                return Err(Error::unexpected_type("non-word"));
+                return Err(Error::unexpected_type("non-word").with_span(nmi));
             }
         }
 
         Ok(IdentList(idents))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::IdentList;
+    use proc_macro2::TokenStream;
+    use FromMeta;
+
+    /// parse a string as a syn::Meta instance.
+    fn pm(tokens: TokenStream) -> ::std::result::Result<syn::Meta, String> {
+        let attribute: syn::Attribute = parse_quote!(#[#tokens]);
+        attribute.interpret_meta().ok_or("Unable to parse".into())
+    }
+
+    fn fm<T: FromMeta>(tokens: TokenStream) -> T {
+        FromMeta::from_meta(&pm(tokens).expect("Tests should pass well-formed input"))
+            .expect("Tests should pass valid input")
+    }
+
+    #[test]
+    fn succeeds() {
+        let idents = fm::<IdentList>(quote!(ignore(Debug, Clone, Eq)));
+        assert_eq!(
+            idents.to_strings(),
+            vec![
+                String::from("Debug"),
+                String::from("Clone"),
+                String::from("Eq")
+            ]
+        );
+    }
+
+    /// Check that the parser rejects non-word members of the list, and that the error
+    /// has an associated span.
+    #[test]
+    fn fails_non_word() {
+        let input = IdentList::from_meta(&pm(quote!(ignore(Debug, Clone = false))).unwrap());
+        let err = input.unwrap_err();
+        assert!(err.has_span());
+    }
+}