Use FfiConverterArrayBuffer not FfiConverterBytes for byte arrays

src/bindings/filters.rs

@@ -108,7 +108,7 @@ pub fn typescript_ffi_converter_name(typ: &impl AsType, askama_values: &dyn aska
         Type::Float64 => "FfiConverterFloat64".into(),
         Type::Boolean => "FfiConverterBool".into(),
         Type::String => "FfiConverterString".into(),
-        Type::Bytes => "FfiConverterBytes".into(),
+        Type::Bytes => "FfiConverterArrayBuffer".into(),
         Type::Timestamp => "FfiConverterTimestamp".into(),
         Type::Duration => "FfiConverterDuration".into(),
         Type::Enum { name, .. } | Type::Record { name, .. } | Type::Object { name, .. } => typescript_ffi_converter_struct_enum_object_name(&name, askama_values)?,
@@ -131,7 +131,7 @@ pub fn typescript_ffi_converter_name(typ: &impl AsType, askama_values: &dyn aska
 
 pub fn typescript_ffi_converter_lift_with(target: String, askama_values: &dyn askama::Values, typ: &impl AsType) -> Result<String> {
     Ok(match typ.as_type() {
-        Type::String | Type::Map { .. } | Type::Sequence { .. } | Type::Enum { .. } | Type::Record { .. } => {
+        Type::String | Type::Bytes | Type::Map { .. } | Type::Sequence { .. } | Type::Enum { .. } | Type::Record { .. } => {
             format!("{}.lift(new UniffiRustBufferValue({target}).consumeIntoUint8Array())", typescript_ffi_converter_name(typ, askama_values)?)
         },
         Type::Optional { inner_type } => {
@@ -143,7 +143,7 @@ pub fn typescript_ffi_converter_lift_with(target: String, askama_values: &dyn as
 
 pub fn typescript_ffi_converter_lower_with(target: String, askama_values: &dyn askama::Values, typ: &impl AsType) -> Result<String> {
     Ok(match typ.as_type() {
-        Type::String | Type::Map { .. } | Type::Sequence { .. } | Type::Enum { .. } | Type::Record { .. } => {
+        Type::String | Type::Bytes | Type::Map { .. } | Type::Sequence { .. } | Type::Enum { .. } | Type::Record { .. } => {
             format!("UniffiRustBufferValue.allocateWithBytes({}.lower({target})).toStruct()", typescript_ffi_converter_name(typ, askama_values)?)
         },
         Type::Optional { inner_type } => {

src/bindings/generator.rs

@@ -140,3 +140,51 @@ pub fn generate_node_bindings(
         index_ts_file_contents,
     })
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn bytes_roundtrip_uses_rust_buffer_serde_in_generated_bindings() {
+        let ci = ComponentInterface::from_webidl(
+            r#"
+            namespace test {
+                bytes round_trip(bytes input);
+            };
+        "#,
+            "crate_name",
+        ).unwrap();
+
+        let bindings = generate_node_bindings(
+            &ci,
+            GenerateNodeBindingsOptions {
+                sys_ts_main_file_name: "test-sys",
+                node_ts_main_file_name: "test-node",
+                out_dirname_api: DirnameApi::Dirname,
+                out_lib_disable_auto_loading: false,
+                out_import_extension: ImportExtension::None,
+                out_node_version: "^18",
+                out_verbose_logs: false,
+                out_lib_path: LibPath::Omitted,
+            },
+        ).unwrap();
+
+        assert!(
+            bindings.node_ts_file_contents.contains("export function roundTrip("),
+            "node.ts should render the bytes round-trip function from the UDL"
+        );
+        assert!(
+            bindings.node_ts_file_contents.contains(
+                "let inputArg = UniffiRustBufferValue.allocateWithBytes(FfiConverterArrayBuffer.lower(input)).toStruct();"
+            ),
+            "node.ts should lower bytes arguments into a RustBuffer struct before the ffi call"
+        );
+        assert!(
+            bindings.node_ts_file_contents.contains(
+                "return FfiConverterArrayBuffer.lift(new UniffiRustBufferValue(returnValue).consumeIntoUint8Array());"
+            ),
+            "node.ts should lift bytes return values from the RustBuffer returned by ffi"
+        );
+    }
+}