Add json and yaml serialization for syncaggregatorselectiondata

spec/altair/syncaggregatorselectiondata.go

@@ -14,7 +14,14 @@
 package altair
 
 import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strconv"
+
 	"github.com/attestantio/go-eth2-client/spec/phase0"
+	"github.com/goccy/go-yaml"
+	"github.com/pkg/errors"
 )
 
 // SyncAggregatorSelectionData is an internal struct for
@@ -23,3 +30,92 @@ type SyncAggregatorSelectionData struct {
 	Slot              phase0.Slot
 	SubcommitteeIndex uint64
 }
+
+// syncAggregatorSelectionDataJSON is the spec representation of the struct.
+type syncAggregatorSelectionDataJSON struct {
+	Slot              string `json:"slot"`
+	SubcommitteeIndex string `json:"subcommittee_index"`
+}
+
+// syncAggregatorSelectionDataYAML is the spec representation of the struct.
+type syncAggregatorSelectionDataYAML struct {
+	Slot              uint64 `yaml:"slot"`
+	SubcommitteeIndex uint64 `yaml:"subcommittee_index"`
+}
+
+// MarshalJSON implements json.Marshaler.
+func (s *SyncAggregatorSelectionData) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&syncAggregatorSelectionDataJSON{
+		Slot:              fmt.Sprintf("%d", s.Slot),
+		SubcommitteeIndex: fmt.Sprintf("%d", s.SubcommitteeIndex),
+	})
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (s *SyncAggregatorSelectionData) UnmarshalJSON(input []byte) error {
+	var syncAggregatorSelectionDataJSON syncAggregatorSelectionDataJSON
+	if err := json.Unmarshal(input, &syncAggregatorSelectionDataJSON); err != nil {
+		return errors.Wrap(err, "invalid JSON")
+	}
+
+	return s.unpack(&syncAggregatorSelectionDataJSON)
+}
+
+func (s *SyncAggregatorSelectionData) unpack(syncAggregatorSelectionDataJSON *syncAggregatorSelectionDataJSON) error {
+	if syncAggregatorSelectionDataJSON.Slot == "" {
+		return errors.New("slot missing")
+	}
+
+	slot, err := strconv.ParseUint(syncAggregatorSelectionDataJSON.Slot, 10, 64)
+	if err != nil {
+		return errors.Wrap(err, "invalid value for slot")
+	}
+
+	s.Slot = phase0.Slot(slot)
+
+	if syncAggregatorSelectionDataJSON.SubcommitteeIndex == "" {
+		return errors.New("subcommittee index missing")
+	}
+
+	subcommitteeIndex, err := strconv.ParseUint(syncAggregatorSelectionDataJSON.SubcommitteeIndex, 10, 64)
+	if err != nil {
+		return errors.Wrap(err, "invalid value for subcommittee index")
+	}
+
+	s.SubcommitteeIndex = subcommitteeIndex
+
+	return nil
+}
+
+// MarshalYAML implements yaml.Marshaler.
+func (s *SyncAggregatorSelectionData) MarshalYAML() ([]byte, error) {
+	yamlBytes, err := yaml.MarshalWithOptions(&syncAggregatorSelectionDataYAML{
+		Slot:              uint64(s.Slot),
+		SubcommitteeIndex: s.SubcommitteeIndex,
+	}, yaml.Flow(true))
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.ReplaceAll(yamlBytes, []byte(`"`), []byte(`'`)), nil
+}
+
+// UnmarshalYAML implements yaml.Unmarshaler.
+func (s *SyncAggregatorSelectionData) UnmarshalYAML(input []byte) error {
+	var syncAggregatorSelectionDataJSON syncAggregatorSelectionDataJSON
+	if err := yaml.Unmarshal(input, &syncAggregatorSelectionDataJSON); err != nil {
+		return err
+	}
+
+	return s.unpack(&syncAggregatorSelectionDataJSON)
+}
+
+// String returns a string version of the structure.
+func (s *SyncAggregatorSelectionData) String() string {
+	data, err := yaml.Marshal(s)
+	if err != nil {
+		return fmt.Sprintf("ERR: %v", err)
+	}
+
+	return string(data)
+}

spec/altair/syncaggregatorselectiondata_test.go

@@ -0,0 +1,160 @@
+// Copyright © 2026 Attestant Limited.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package altair_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/attestantio/go-eth2-client/spec/altair"
+	"github.com/goccy/go-yaml"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSyncAggregatorSelectionDataJSON(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []byte
+		err   string
+	}{
+		{
+			name: "Empty",
+			err:  "unexpected end of JSON input",
+		},
+		{
+			name:  "JSONBad",
+			input: []byte("[]"),
+			err:   "invalid JSON: json: cannot unmarshal array into Go value of type altair.syncAggregatorSelectionDataJSON",
+		},
+		{
+			name:  "SlotMissing",
+			input: []byte(`{"subcommittee_index":"3"}`),
+			err:   "slot missing",
+		},
+		{
+			name:  "SlotWrongType",
+			input: []byte(`{"slot":true,"subcommittee_index":"3"}`),
+			err:   "invalid JSON: json: cannot unmarshal bool into Go struct field syncAggregatorSelectionDataJSON.slot of type string",
+		},
+		{
+			name:  "SlotInvalid",
+			input: []byte(`{"slot":"-1","subcommittee_index":"3"}`),
+			err:   "invalid value for slot: strconv.ParseUint: parsing \"-1\": invalid syntax",
+		},
+		{
+			name:  "SubcommitteeIndexMissing",
+			input: []byte(`{"slot":"1"}`),
+			err:   "subcommittee index missing",
+		},
+		{
+			name:  "SubcommitteeIndexWrongType",
+			input: []byte(`{"slot":"1","subcommittee_index":true}`),
+			err:   "invalid JSON: json: cannot unmarshal bool into Go struct field syncAggregatorSelectionDataJSON.subcommittee_index of type string",
+		},
+		{
+			name:  "SubcommitteeIndexInvalid",
+			input: []byte(`{"slot":"1","subcommittee_index":"-1"}`),
+			err:   "invalid value for subcommittee index: strconv.ParseUint: parsing \"-1\": invalid syntax",
+		},
+		{
+			name:  "Valid",
+			input: []byte(`{"slot":"1","subcommittee_index":"3"}`),
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			var res altair.SyncAggregatorSelectionData
+			err := json.Unmarshal(test.input, &res)
+			if test.err != "" {
+				require.EqualError(t, err, test.err)
+			} else {
+				require.NoError(t, err)
+				rt, err := json.Marshal(&res)
+				require.NoError(t, err)
+				assert.Equal(t, string(test.input), string(rt))
+			}
+		})
+	}
+}
+
+func TestSyncAggregatorSelectionDataYAML(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []byte
+		err   string
+	}{
+		{
+			name:  "Good",
+			input: []byte(`{slot: 1, subcommittee_index: 3}`),
+		},
+		{
+			name:  "YAMLBad",
+			input: []byte("[]"),
+			err:   "[1:1] sequence was used where mapping is expected\n>  1 | []\n       ^\n",
+		},
+		{
+			name:  "SlotMissing",
+			input: []byte(`{"subcommittee_index":"3"}`),
+			err:   "slot missing",
+		},
+		{
+			name:  "SlotWrongType",
+			input: []byte(`{"slot":true,"subcommittee_index":"3"}`),
+			err:   "invalid value for slot: strconv.ParseUint: parsing \"true\": invalid syntax",
+		},
+		{
+			name:  "SlotInvalid",
+			input: []byte(`{"slot":"-1","subcommittee_index":"3"}`),
+			err:   "invalid value for slot: strconv.ParseUint: parsing \"-1\": invalid syntax",
+		},
+		{
+			name:  "SubcommitteeIndexMissing",
+			input: []byte(`{"slot":"1"}`),
+			err:   "subcommittee index missing",
+		},
+		{
+			name:  "SubcommitteeIndexWrongType",
+			input: []byte(`{"slot":"1","subcommittee_index":true}`),
+			err:   "invalid JSON: json: cannot unmarshal bool into Go struct field syncAggregatorSelectionDataJSON.subcommittee_index of type string",
+		},
+		{
+			name:  "SubcommitteeIndexInvalid",
+			input: []byte(`{"slot":"1","subcommittee_index":"-1"}`),
+			err:   "invalid value for subcommittee index: strconv.ParseUint: parsing \"-1\": invalid syntax",
+		},
+		{
+			name:  "Valid",
+			input: []byte(`{"slot":"1","subcommittee_index":"3"}`),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			var res altair.SyncAggregatorSelectionData
+			err := yaml.Unmarshal(test.input, &res)
+			if test.err != "" {
+				require.EqualError(t, err, test.err)
+			} else {
+				require.NoError(t, err)
+				rt, err := yaml.Marshal(&res)
+				require.NoError(t, err)
+				assert.Equal(t, string(rt), res.String())
+				rt = bytes.TrimSuffix(rt, []byte("\n"))
+				assert.Equal(t, string(test.input), string(rt))
+			}
+		})
+	}
+}