Add totalDifficulty field to JSON-RPC schema of Celo1 block (#310)

* Add totalDifficulty field to JSON-RPC response for Celo1 header & block

* Fix test

* Remove new line

---------

Co-authored-by: piersy <[email protected]>

Author: Kourin1996

internal/ethapi/api.go

@@ -844,7 +844,7 @@ func (api *BlockChainAPI) GetHeaderByNumber(ctx context.Context, number rpc.Bloc
 	header, err := api.b.HeaderByNumber(ctx, number)
 	if header != nil && err == nil {
 		header := PopulatePreGingerbreadHeaderFields(ctx, api.b, header)
-		response := RPCMarshalHeader(header)
+		response := RPCMarshalHeader(header, isCelo1Block(api.b.ChainConfig(), header.Time))
 		if number == rpc.PendingBlockNumber && api.b.ChainConfig().Optimism == nil {
 			// Pending header need to nil out a few fields
 			for _, field := range []string{"hash", "nonce", "miner"} {
@@ -861,7 +861,7 @@ func (api *BlockChainAPI) GetHeaderByHash(ctx context.Context, hash common.Hash)
 	header, _ := api.b.HeaderByHash(ctx, hash)
 	if header != nil {
 		header := PopulatePreGingerbreadHeaderFields(ctx, api.b, header)
-		return RPCMarshalHeader(header)
+		return RPCMarshalHeader(header, isCelo1Block(api.b.ChainConfig(), header.Time))
 	}
 	return nil
 }
@@ -1520,7 +1520,7 @@ func (api *BlockChainAPI) EstimateGas(ctx context.Context, args TransactionArgs,
 }
 
 // RPCMarshalHeader converts the given header to the RPC output .
-func RPCMarshalHeader(head *types.Header) map[string]interface{} {
+func RPCMarshalHeader(head *types.Header, isCelo1 bool) map[string]interface{} {
 	result := map[string]interface{}{
 		"number":           (*hexutil.Big)(head.Number),
 		"hash":             head.Hash(),
@@ -1557,14 +1557,23 @@ func RPCMarshalHeader(head *types.Header) map[string]interface{} {
 	if head.RequestsHash != nil {
 		result["requestsRoot"] = head.RequestsHash
 	}
+	if isCelo1 {
+		result["totalDifficulty"] = (*hexutil.Big)(new(big.Int).Add(head.Number, common.Big1))
+	}
 	return result
 }
 
+// isCelo1Block determines whether the given block is a Celo1 block
+// based on the chain config and the provided block time
+func isCelo1Block(config *params.ChainConfig, blockTime uint64) bool {
+	return config.Cel2Time != nil && !config.IsCel2(blockTime)
+}
+
 // RPCMarshalBlock converts the given block to the RPC output which depends on fullTx. If inclTx is true transactions are
 // returned. When fullTx is true the returned block contains full transaction details, otherwise it will only contain
 // transaction hashes.
 func RPCMarshalBlock(ctx context.Context, block *types.Block, inclTx bool, fullTx bool, config *params.ChainConfig, backend Backend) (map[string]interface{}, error) {
-	fields := RPCMarshalHeader(block.Header())
+	fields := RPCMarshalHeader(block.Header(), isCelo1Block(config, block.Header().Time))
 	fields["size"] = hexutil.Uint64(block.Size())
 
 	if inclTx {

internal/ethapi/celo_api_test.go

@@ -1,13 +1,15 @@
 package ethapi
 
 import (
+	"context"
 	"math/big"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/internal/blocktest"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -531,3 +533,83 @@ func checkTxFields(
 	assert.Equal(t, (*hexutil.Big)(tx.GatewayFee()), rpcTx.GatewayFee)
 	assert.Equal(t, tx.GatewayFeeRecipient(), rpcTx.GatewayFeeRecipient)
 }
+
+// Test_isCelo1Block tests isCelo1Block function to determine whether the given block time
+// corresponds to Celo1 chain based on the provided chain configuration
+func Test_isCelo1Block(t *testing.T) {
+	cel2Time := uint64(1000)
+
+	t.Run("Non-Celo", func(t *testing.T) {
+		res := isCelo1Block(&params.ChainConfig{
+			Cel2Time: nil,
+		}, 1000)
+
+		assert.False(t, res)
+	})
+
+	t.Run("Celo1", func(t *testing.T) {
+		res := isCelo1Block(&params.ChainConfig{
+			Cel2Time: &cel2Time,
+		}, 500)
+
+		assert.True(t, res)
+	})
+
+	t.Run("Celo2", func(t *testing.T) {
+		res := isCelo1Block(&params.ChainConfig{
+			Cel2Time: &cel2Time,
+		}, 1000)
+
+		assert.False(t, res)
+	})
+}
+
+// TestRPCMarshalBlock_Celo1TotalDifficulty tests the RPCMarshalBlock function, specifically for totalDifficulty field
+// It validates the result has `totalDifficulty` field only if it's Celo1 block
+func TestRPCMarshalBlock_Celo1TotalDifficulty(t *testing.T) {
+	t.Parallel()
+
+	blockTime := uint64(1000)
+	block := types.NewBlock(&types.Header{Number: big.NewInt(100), Time: blockTime}, &types.Body{Transactions: []*types.Transaction{}}, nil, blocktest.NewHasher())
+
+	marshalBlock := func(t *testing.T, config *params.ChainConfig) map[string]interface{} {
+		t.Helper()
+
+		resp, err := RPCMarshalBlock(context.Background(), block, false, false, config, testBackend{})
+		if err != nil {
+			require.NoError(t, err)
+		}
+
+		return resp
+	}
+
+	t.Run("Non-Celo", func(t *testing.T) {
+		config := *params.MainnetChainConfig
+
+		res := marshalBlock(t, &config)
+
+		assert.Equal(t, nil, res["totalDifficulty"])
+	})
+
+	t.Run("Celo1", func(t *testing.T) {
+		expected := (*hexutil.Big)(new(big.Int).Add(block.Number(), common.Big1))
+
+		cel2Time := blockTime + 500
+		config := *params.MainnetChainConfig
+		config.Cel2Time = &cel2Time
+
+		res := marshalBlock(t, &config)
+
+		assert.Equal(t, expected, res["totalDifficulty"])
+	})
+
+	t.Run("Celo2", func(t *testing.T) {
+		cel2Time := blockTime - 500
+		config := *params.MainnetChainConfig
+		config.Cel2Time = &cel2Time
+
+		res := marshalBlock(t, &config)
+
+		assert.Equal(t, nil, res["totalDifficulty"])
+	})
+}