rpc: use correct stringer-method for serializing BlockNumberOrHash #28358 (#1006)

The String() version of BlockNumberOrHash uses decimal for all block numbers, including negative ones used to indicate labels. Switch to using BlockNumber.String() which encodes it correctly for use in the JSON-RPC API.

Co-authored-by: Adrian Sutton <adrian@oplabs.co>

rpc/types.go

@@ -235,6 +235,16 @@ func (bnh *BlockNumberOrHash) Number() (BlockNumber, bool) {
 	return BlockNumber(0), false
 }
 
+func (bnh *BlockNumberOrHash) String() string {
+	if bnh.BlockNumber != nil {
+		return bnh.BlockNumber.String()
+	}
+	if bnh.BlockHash != nil {
+		return bnh.BlockHash.String()
+	}
+	return "nil"
+}
+
 func (bnh *BlockNumberOrHash) Hash() (common.Hash, bool) {
 	if bnh.BlockHash != nil {
 		return *bnh.BlockHash, true

rpc/types_test.go

@@ -155,3 +155,24 @@ func TestBlockNumberOrHash_WithNumber_MarshalAndUnmarshal(t *testing.T) {
 		})
 	}
 }
+
+func TestBlockNumberOrHash_StringAndUnmarshal(t *testing.T) {
+	tests := []BlockNumberOrHash{
+		BlockNumberOrHashWithNumber(math.MaxInt64),
+		BlockNumberOrHashWithNumber(PendingBlockNumber),
+		BlockNumberOrHashWithNumber(LatestBlockNumber),
+		BlockNumberOrHashWithNumber(EarliestBlockNumber),
+		BlockNumberOrHashWithNumber(32),
+		BlockNumberOrHashWithHash(common.Hash{0xaa}, false),
+	}
+	for _, want := range tests {
+		marshalled, _ := json.Marshal(want.String())
+		var have BlockNumberOrHash
+		if err := json.Unmarshal(marshalled, &have); err != nil {
+			t.Fatalf("cannot unmarshal (%v): %v", string(marshalled), err)
+		}
+		if !reflect.DeepEqual(want, have) {
+			t.Fatalf("wrong result: have %v, want %v", have, want)
+		}
+	}
+}