test(proto): add unit tests for metadata descriptors

- Add tests for StorageNodeMetadataDescriptor and LogStreamReplicaMetadataDescriptor
- Test methods: ToStorageNodeDescriptor, GetLogStream, Head, and Tail
- Ensure proper coverage for edge cases and nil values

proto/snpb/metadata.go

@@ -5,6 +5,9 @@ import (
 	"github.com/kakao/varlog/proto/varlogpb"
 )
 
+// ToStorageNodeDescriptor converts a StorageNodeMetadataDescriptor to a
+// varlogpb.StorageNodeDescriptor. It returns nil if the
+// StorageNodeMetadataDescriptor is nil.
 func (snmd *StorageNodeMetadataDescriptor) ToStorageNodeDescriptor() *varlogpb.StorageNodeDescriptor {
 	if snmd == nil {
 		return nil
@@ -19,6 +22,9 @@ func (snmd *StorageNodeMetadataDescriptor) ToStorageNodeDescriptor() *varlogpb.S
 	return snd
 }
 
+// GetLogStream retrieves a LogStreamReplicaMetadataDescriptor by its
+// LogStreamID. It returns the LogStreamReplicaMetadataDescriptor and true if
+// found, otherwise an empty descriptor and false.
 func (snmd *StorageNodeMetadataDescriptor) GetLogStream(logStreamID types.LogStreamID) (LogStreamReplicaMetadataDescriptor, bool) {
 	logStreams := snmd.GetLogStreamReplicas()
 	for i := range logStreams {
@@ -29,6 +35,10 @@ func (snmd *StorageNodeMetadataDescriptor) GetLogStream(logStreamID types.LogStr
 	return LogStreamReplicaMetadataDescriptor{}, false
 }
 
+// Head returns the varlogpb.LogEntryMeta corresponding to the local low
+// watermark of the LogStreamReplicaMetadataDescriptor. The "head" represents
+// the earliest log entry in the log stream replica. It returns an empty
+// varlogpb.LogEntryMeta if the LogStreamReplicaMetadataDescriptor is nil.
 func (lsrmd *LogStreamReplicaMetadataDescriptor) Head() varlogpb.LogEntryMeta {
 	if lsrmd == nil {
 		return varlogpb.LogEntryMeta{}
@@ -41,6 +51,10 @@ func (lsrmd *LogStreamReplicaMetadataDescriptor) Head() varlogpb.LogEntryMeta {
 	}
 }
 
+// Tail returns the varlogpb.LogEntryMeta corresponding to the local high
+// watermark of the LogStreamReplicaMetadataDescriptor. The "tail" represents
+// the latest log entry in the log stream replica. It returns an empty
+// varlogpb.LogEntryMeta if the LogStreamReplicaMetadataDescriptor is nil.
 func (lsrmd *LogStreamReplicaMetadataDescriptor) Tail() varlogpb.LogEntryMeta {
 	if lsrmd == nil {
 		return varlogpb.LogEntryMeta{}

proto/snpb/metadata_test.go

@@ -0,0 +1,191 @@
+package snpb_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/kakao/varlog/pkg/types"
+	"github.com/kakao/varlog/proto/snpb"
+	"github.com/kakao/varlog/proto/varlogpb"
+)
+
+func TestStorageNodeMetadataDescriptor_ToStorageNodeDescriptor(t *testing.T) {
+	tcs := []struct {
+		snmd *snpb.StorageNodeMetadataDescriptor
+		want *varlogpb.StorageNodeDescriptor
+		name string
+	}{
+		{
+			name: "Nil",
+			snmd: nil,
+			want: nil,
+		},
+		{
+			name: "NonNil",
+			snmd: &snpb.StorageNodeMetadataDescriptor{
+				StorageNode: varlogpb.StorageNode{
+					StorageNodeID: types.MinStorageNodeID,
+					Address:       "node1",
+				},
+				Storages: []varlogpb.StorageDescriptor{
+					{Path: "/path1"},
+					{Path: "/path2"},
+				},
+			},
+			want: &varlogpb.StorageNodeDescriptor{
+				StorageNode: varlogpb.StorageNode{
+					StorageNodeID: types.MinStorageNodeID,
+					Address:       "node1",
+				},
+				Paths: []string{"/path1", "/path2"},
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.snmd.ToStorageNodeDescriptor()
+			require.Equal(t, tc.want, got)
+		})
+	}
+}
+
+func TestStorageNodeMetadataDescriptor_GetLogStream(t *testing.T) {
+	tcs := []struct {
+		name        string
+		logStreamID types.LogStreamID
+		want        snpb.LogStreamReplicaMetadataDescriptor
+		wantFound   bool
+	}{
+		{
+			name:        "Found",
+			logStreamID: types.LogStreamID(1),
+			want: snpb.LogStreamReplicaMetadataDescriptor{
+				LogStreamReplica: varlogpb.LogStreamReplica{
+					TopicLogStream: varlogpb.TopicLogStream{
+						LogStreamID: types.LogStreamID(1),
+					},
+				},
+			},
+			wantFound: true,
+		},
+		{
+			name:        "NotFound",
+			logStreamID: types.LogStreamID(3),
+			want:        snpb.LogStreamReplicaMetadataDescriptor{},
+			wantFound:   false,
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			snmd := &snpb.StorageNodeMetadataDescriptor{
+				LogStreamReplicas: []snpb.LogStreamReplicaMetadataDescriptor{
+					{
+						LogStreamReplica: varlogpb.LogStreamReplica{
+							TopicLogStream: varlogpb.TopicLogStream{
+								LogStreamID: types.LogStreamID(1),
+							},
+						},
+					},
+					{
+						LogStreamReplica: varlogpb.LogStreamReplica{
+							TopicLogStream: varlogpb.TopicLogStream{
+								LogStreamID: types.LogStreamID(2),
+							},
+						},
+					},
+				},
+			}
+
+			got, found := snmd.GetLogStream(tc.logStreamID)
+			require.Equal(t, tc.wantFound, found)
+			require.Equal(t, tc.want, got)
+		})
+	}
+}
+
+func TestLogStreamReplicaMetadataDescriptor_Head(t *testing.T) {
+	tcs := []struct {
+		lsrmd *snpb.LogStreamReplicaMetadataDescriptor
+		name  string
+		want  varlogpb.LogEntryMeta
+	}{
+		{
+			name:  "Nil",
+			lsrmd: nil,
+			want:  varlogpb.LogEntryMeta{},
+		},
+		{
+			name: "NonNil",
+			lsrmd: &snpb.LogStreamReplicaMetadataDescriptor{
+				LogStreamReplica: varlogpb.LogStreamReplica{
+					TopicLogStream: varlogpb.TopicLogStream{
+						TopicID:     types.TopicID(1),
+						LogStreamID: types.LogStreamID(2),
+					},
+				},
+				LocalLowWatermark: varlogpb.LogSequenceNumber{
+					LLSN: types.LLSN(3),
+					GLSN: types.GLSN(4),
+				},
+			},
+			want: varlogpb.LogEntryMeta{
+				TopicID:     1,
+				LogStreamID: 2,
+				LLSN:        3,
+				GLSN:        4,
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.lsrmd.Head()
+			require.Equal(t, tc.want, got)
+		})
+	}
+}
+
+func TestLogStreamReplicaMetadataDescriptor_Tail(t *testing.T) {
+	tcs := []struct {
+		lsrmd *snpb.LogStreamReplicaMetadataDescriptor
+		name  string
+		want  varlogpb.LogEntryMeta
+	}{
+		{
+			name:  "Nil",
+			lsrmd: nil,
+			want:  varlogpb.LogEntryMeta{},
+		},
+		{
+			name: "NonNil",
+			lsrmd: &snpb.LogStreamReplicaMetadataDescriptor{
+				LogStreamReplica: varlogpb.LogStreamReplica{
+					TopicLogStream: varlogpb.TopicLogStream{
+						TopicID:     types.TopicID(1),
+						LogStreamID: types.LogStreamID(2),
+					},
+				},
+				LocalHighWatermark: varlogpb.LogSequenceNumber{
+					LLSN: types.LLSN(5),
+					GLSN: types.GLSN(6),
+				},
+			},
+			want: varlogpb.LogEntryMeta{
+				TopicID:     1,
+				LogStreamID: 2,
+				LLSN:        5,
+				GLSN:        6,
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.lsrmd.Tail()
+			require.Equal(t, tc.want, got)
+		})
+	}
+}