chore: add side-by-side tests with official proto.Marshal and Unmarshal

This tests ensures that our encoding is compatible with official proto modules.

Closes #2

Signed-off-by: Dmitriy Matrenichev <dmitry.matrenichev@siderolabs.com>

marshal.go

@@ -109,7 +109,7 @@ func (m *marshaller) encodeFields(val reflect.Value, fieldsData []FieldData) {
 	}
 
 	if noneEncoded {
-		panic("struct has no marshallable fields")
+		panic(fmt.Errorf("struct '%s' has no marshallable fields", val.Type().Name()))
 	}
 }
 

messages/helpers_test.go

@@ -0,0 +1,73 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package messages_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/proto"
+
+	"github.com/siderolabs/protoenc"
+)
+
+func shouldBeEqual[T any](t *testing.T, left, right T) {
+	t.Helper()
+
+	opts := makeOpts[T]()
+
+	if !cmp.Equal(left, right, opts...) {
+		t.Log(cmp.Diff(left, right, opts...))
+		t.FailNow()
+	}
+}
+
+func makeOpts[T any]() []cmp.Option {
+	var zero T
+
+	typ := reflect.TypeOf(zero)
+	for typ.Kind() == reflect.Ptr {
+		typ = typ.Elem()
+	}
+
+	if typ.Kind() == reflect.Struct {
+		return []cmp.Option{cmpopts.IgnoreUnexported(reflect.New(typ).Elem().Interface())}
+	}
+
+	return nil
+}
+
+type msg[T any] interface {
+	*T
+	proto.Message
+}
+
+func protoUnmarshal[T any, V msg[T]](t *testing.T, data []byte) V {
+	t.Helper()
+	var msg T
+	err := proto.Unmarshal(data, V(&msg))
+	require.NoError(t, err)
+	return V(&msg)
+}
+
+func ourUnmarshal[T any](t *testing.T, data []byte) T {
+	t.Helper()
+	var msg T
+	err := protoenc.Unmarshal(data, &msg)
+	require.NoError(t, err)
+	return msg
+}
+
+func must[T any](v T, err error) func(t *testing.T) T {
+	return func(t *testing.T) T {
+		t.Helper()
+		require.NoError(t, err)
+
+		return v
+	}
+}