From 5b8206d5fb987461a81668c4271b8686c8f941d0 Mon Sep 17 00:00:00 2001
From: Dmitry Zenovich <dmitry.zenovich@toptal.com>
Date: Tue, 3 Aug 2021 16:47:02 +0300
Subject: [PATCH] marshal rpc.BlockNumber correctly

---
 rpc/types.go      | 16 ++++++++++++++++
 rpc/types_test.go | 31 +++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/rpc/types.go b/rpc/types.go
index d1b878c7858ff..a512845b9e755 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -97,6 +97,22 @@ func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// MarshalText implements encoding.TextMarshaler. It marshals:
+// - "latest", "earliest" or "pending" as strings
+// - other numbers as hex
+func (bn BlockNumber) MarshalText() ([]byte, error) {
+	switch bn {
+	case EarliestBlockNumber:
+		return []byte("earliest"), nil
+	case LatestBlockNumber:
+		return []byte("latest"), nil
+	case PendingBlockNumber:
+		return []byte("pending"), nil
+	default:
+		return hexutil.Uint64(bn).MarshalText()
+	}
+}
+
 func (bn BlockNumber) Int64() int64 {
 	return (int64)(bn)
 }
diff --git a/rpc/types_test.go b/rpc/types_test.go
index 89b0c9171a145..f110dee7c6ffe 100644
--- a/rpc/types_test.go
+++ b/rpc/types_test.go
@@ -18,6 +18,7 @@ package rpc
 
 import (
 	"encoding/json"
+	"reflect"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -122,3 +123,33 @@ func TestBlockNumberOrHash_UnmarshalJSON(t *testing.T) {
 		}
 	}
 }
+
+func TestBlockNumberOrHash_WithNumber_MarshalAndUnmarshal(t *testing.T) {
+	tests := []struct {
+		name   string
+		number int64
+	}{
+		{"max", math.MaxInt64},
+		{"pending", int64(PendingBlockNumber)},
+		{"latest", int64(LatestBlockNumber)},
+		{"earliest", int64(EarliestBlockNumber)},
+	}
+	for _, test := range tests {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			bnh := BlockNumberOrHashWithNumber(BlockNumber(test.number))
+			marshalled, err := json.Marshal(bnh)
+			if err != nil {
+				t.Fatal("cannot marshal:", err)
+			}
+			var unmarshalled BlockNumberOrHash
+			err = json.Unmarshal(marshalled, &unmarshalled)
+			if err != nil {
+				t.Fatal("cannot unmarshal:", err)
+			}
+			if !reflect.DeepEqual(bnh, unmarshalled) {
+				t.Fatalf("wrong result: expected %v, got %v", bnh, unmarshalled)
+			}
+		})
+	}
+}