improve code and add tests

packages/derive/src/into_event.rs

@@ -22,7 +22,7 @@ fn scan_to_string_fn(field: &Field) -> Result<Option<proc_macro2::TokenStream>>
     if filtered.is_empty() {
         Ok(None)
     } else {
-        Ok(Some(filtered[0].tokens.clone()))
+        Ok(Some(filtered[0].parse_args()?))
     }
 }
 
@@ -35,7 +35,7 @@ fn has_use_to_string(field: &Field) -> Result<bool> {
     if filtered.clone().any(|a| !a.tokens.is_empty()) {
         return Err(Error::new(
             field.span(),
-            "[IntoEvent] attribute `use_to_string` has some value. If you intend to specify the cast function to string, use `to_string_fn` instead.",
+            "[IntoEvent] An attribute `use_to_string` has some value. If you intend to specify the cast function to string, use `to_string_fn` instead.",
         ));
     }
     Ok(filtered.next().is_some())
@@ -88,12 +88,11 @@ fn make_init_from_struct(id: Ident, struct_data: DataStruct) -> Result<proc_macr
     Ok(gen)
 }
 
-/// derive `IntoEvent` from a derive input. The input needs to be a struct.
-pub fn derive_into_event(input: DeriveInput) -> TokenStream {
+fn derive_into_event_impl(input: DeriveInput) -> proc_macro2::TokenStream {
     match input.data {
-        syn::Data::Struct(struct_data) => make_init_from_struct(input.ident, struct_data)
-            .unwrap_or_else(|e| e.to_compile_error())
-            .into(),
+        syn::Data::Struct(struct_data) => {
+            make_init_from_struct(input.ident, struct_data).unwrap_or_else(|e| e.to_compile_error())
+        }
         syn::Data::Enum(enum_data) => Error::new(
             enum_data.enum_token.span,
             "[IntoEvent] `derive(IntoEvent)` cannot be applied to Enum.",
@@ -108,3 +107,126 @@ pub fn derive_into_event(input: DeriveInput) -> TokenStream {
         .into(),
     }
 }
+
+/// derive `IntoEvent` from a derive input. The input needs to be a struct.
+pub fn derive_into_event(input: DeriveInput) -> TokenStream {
+    derive_into_event_impl(input).into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use proc_macro2::TokenStream;
+    use syn::parse_quote;
+
+    fn expect_compile_error(ts: TokenStream, msg: &str) {
+        assert!(
+            ts.to_string().starts_with("compile_error ! {"),
+            "Code does not raise compile error: `{}`",
+            ts.to_string()
+        );
+
+        assert!(
+            ts.to_string().contains(msg),
+            "Error does not have expected message \"{}\": `{}`",
+            msg,
+            ts.to_string()
+        );
+    }
+
+    #[test]
+    fn test_doc_example() {
+        let input: DeriveInput = parse_quote! {
+            struct StructName {
+                field_name_1: field_type_1,
+                #[use_to_string]
+                field_name_2: field_type_2,
+                #[to_string_fn(cast_fn_3)]
+                field_name_3: field_type_3,
+            }
+        };
+        let result_implement = derive_into_event_impl(input);
+        let expected: TokenStream = parse_quote! {
+            impl Into<cosmwasm_std::Event> for StructName {
+                fn into(self) -> cosmwasm_std::Event {
+                    cosmwasm_std::Event::new("struct_name")
+                        .add_attribute(stringify!(field_name_1), self.field_name_1)
+                        .add_attribute(stringify!(field_name_2), self.field_name_2.to_string())
+                        .add_attribute(stringify!(field_name_3), cast_fn_3 (self.field_name_3))
+                }
+            }
+        };
+        assert_eq!(expected.to_string(), result_implement.to_string())
+    }
+
+    #[test]
+    fn test_error_multiple_to_string_functions() {
+        let input: DeriveInput = parse_quote! {
+            struct StructName {
+                #[to_string_fn(cast_fn_1)]
+                #[to_string_fn(cast_fn_1)]
+                field_name_1: field_type_1,
+            }
+        };
+        let result_implement = derive_into_event_impl(input);
+        expect_compile_error(
+            result_implement,
+            "[IntoEvent] Only one or zero `to_string_fn`",
+        );
+    }
+
+    #[test]
+    fn test_error_use_to_string_has_value() {
+        let input: DeriveInput = parse_quote! {
+            struct StructName {
+                #[use_to_string(foo)]
+                field_name_1: field_type_1,
+            }
+        };
+        let result_implement = derive_into_event_impl(input);
+        expect_compile_error(
+            result_implement,
+            "[IntoEvent] An attribute `use_to_string` has some value",
+        );
+    }
+
+    #[test]
+    fn test_error_both_two_attributes_is_used() {
+        let input: DeriveInput = parse_quote! {
+            struct StructName {
+                #[use_to_string]
+                #[to_string_fn(cast_fn_1)]
+                field_name_1: field_type_1,
+            }
+        };
+        let result_implement = derive_into_event_impl(input);
+        expect_compile_error(
+            result_implement,
+            "[IntoEvent] Both `use_to_string` and `to_string_fn`",
+        );
+    }
+
+    #[test]
+    fn test_error_derive_enum() {
+        let input: DeriveInput = parse_quote! {
+            enum Enum {}
+        };
+        let result_implement = derive_into_event_impl(input);
+        expect_compile_error(
+            result_implement,
+            "[IntoEvent] `derive(IntoEvent)` cannot be applied to Enum",
+        );
+    }
+
+    #[test]
+    fn test_error_derive_union() {
+        let input: DeriveInput = parse_quote! {
+            union Union {}
+        };
+        let result_implement = derive_into_event_impl(input);
+        expect_compile_error(
+            result_implement,
+            "[IntoEvent] `derive(IntoEvent)` cannot be applied to Union",
+        );
+    }
+}

packages/derive/src/lib.rs

@@ -109,12 +109,12 @@ pub fn entry_point(_attr: TokenStream, mut item: TokenStream) -> TokenStream {
 /// Output AST:
 ///
 /// ```no_test
-/// impl Into<cosmwasm::Event> for `StructName` {
-///     fn into(self) -> Event {
-///         Event::new("struct_name")
-///             .add_attribute("field_name_1", self.field_value_1)
-///             .add_attribute("field_name_2", self.field_value_2.to_string())
-///             .add_attribute("field_name_3", casting_fn(self.field_value_3))
+/// impl Into<cosmwasm_std::Event> for StructName {
+///     fn into(self) -> cosmwasm_std::Event {
+///         cosmwasm_std::Event::new("struct_name")
+///             .add_attribute("field_name_1", self.field_name_1)
+///             .add_attribute("field_name_2", self.field_name_2.to_string())
+///             .add_attribute("field_name_3", cast_fn_3(self.field_name_3))
 ///     }
 /// }
 /// ```