diff --git a/proto/varlogpb/replica_test.go b/proto/varlogpb/replica_test.go
new file mode 100644
index 000000000..ca9a337c5
--- /dev/null
+++ b/proto/varlogpb/replica_test.go
@@ -0,0 +1,152 @@
+package varlogpb_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/kakao/varlog/proto/varlogpb"
+)
+
+func TestEqualReplicas(t *testing.T) {
+	tcs := []struct {
+		name string
+		xs   []varlogpb.LogStreamReplica
+		ys   []varlogpb.LogStreamReplica
+		want bool
+	}{
+		{
+			name: "EqualReplicas",
+			xs: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			ys: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			want: true,
+		},
+		{
+			name: "DifferentLengths",
+			xs: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			ys:   []varlogpb.LogStreamReplica{},
+			want: false,
+		},
+		{
+			name: "DifferentStorageNodeID",
+			xs: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			ys: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 2},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			want: false,
+		},
+		{
+			name: "DifferentLogStreamID",
+			xs: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			ys: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 2},
+				},
+			},
+			want: false,
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			got := varlogpb.EqualReplicas(tc.xs, tc.ys)
+			require.Equal(t, tc.want, got)
+		})
+	}
+}
+
+func TestValidReplicas(t *testing.T) {
+	tcs := []struct {
+		name     string
+		replicas []varlogpb.LogStreamReplica
+		wantErr  bool
+	}{
+		{
+			name: "ValidReplicas",
+			replicas: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 2},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name:     "NoReplicas",
+			replicas: []varlogpb.LogStreamReplica{},
+			wantErr:  true,
+		},
+		{
+			name: "LogStreamIDMismatch",
+			replicas: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 2},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 2},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "StorageNodeIDDuplicated",
+			replicas: []varlogpb.LogStreamReplica{
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+				{
+					StorageNode:    varlogpb.StorageNode{StorageNodeID: 1},
+					TopicLogStream: varlogpb.TopicLogStream{LogStreamID: 1},
+				},
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			err := varlogpb.ValidReplicas(tc.replicas)
+			if tc.wantErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}