eth_getTransactionCount implementation (#91)

* Implemented eth_getTransactionCount endpoint

* Linting fixes

x/evm/querier.go

@@ -1,6 +1,8 @@
 package evm
 
 import (
+	"math/big"
+
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/ethermint/version"
@@ -8,7 +10,6 @@ import (
 	ethcmn "github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	abci "github.com/tendermint/tendermint/abci/types"
-	"math/big"
 )
 
 // Supported endpoints
@@ -18,6 +19,7 @@ const (
 	QueryBlockNumber     = "blockNumber"
 	QueryStorage         = "storage"
 	QueryCode            = "code"
+	QueryNonce           = "nonce"
 )
 
 // NewQuerier is the module level router for state queries
@@ -34,6 +36,8 @@ func NewQuerier(keeper Keeper) sdk.Querier {
 			return queryStorage(ctx, path, keeper)
 		case QueryCode:
 			return queryCode(ctx, path, keeper)
+		case QueryNonce:
+			return queryNonce(ctx, path, keeper)
 		default:
 			return nil, sdk.ErrUnknownRequest("unknown query endpoint")
 		}
@@ -103,3 +107,15 @@ func queryCode(ctx sdk.Context, path []string, keeper Keeper) ([]byte, sdk.Error
 
 	return res, nil
 }
+
+func queryNonce(ctx sdk.Context, path []string, keeper Keeper) ([]byte, sdk.Error) {
+	addr := ethcmn.BytesToAddress([]byte(path[1]))
+	nonce := keeper.GetNonce(ctx, addr)
+	nRes := types.QueryResNonce{Nonce: nonce}
+	res, err := codec.MarshalJSONIndent(keeper.cdc, nRes)
+	if err != nil {
+		panic("could not marshal result to JSON")
+	}
+
+	return res, nil
+}

x/evm/types/querier.go

@@ -1,10 +1,12 @@
 package types
 
 import (
-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"math/big"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
 )
 
+// QueryResProtocolVersion is response type for protocol version query
 type QueryResProtocolVersion struct {
 	Version string `json:"result"`
 }
@@ -13,6 +15,7 @@ func (q QueryResProtocolVersion) String() string {
 	return q.Version
 }
 
+// QueryResBalance is response type for balance query
 type QueryResBalance struct {
 	Balance *hexutil.Big `json:"result"`
 }
@@ -21,6 +24,7 @@ func (q QueryResBalance) String() string {
 	return q.Balance.String()
 }
 
+// QueryResBlockNumber is response type for block number query
 type QueryResBlockNumber struct {
 	Number *big.Int `json:"result"`
 }
@@ -29,6 +33,7 @@ func (q QueryResBlockNumber) String() string {
 	return q.Number.String()
 }
 
+// QueryResStorage is response type for storage query
 type QueryResStorage struct {
 	Value []byte `json:"value"`
 }
@@ -37,6 +42,7 @@ func (q QueryResStorage) String() string {
 	return string(q.Value)
 }
 
+// QueryResCode is response type for code query
 type QueryResCode struct {
 	Code []byte
 }
@@ -44,3 +50,12 @@ type QueryResCode struct {
 func (q QueryResCode) String() string {
 	return string(q.Code)
 }
+
+// QueryResNonce is response type for Nonce query
+type QueryResNonce struct {
+	Nonce uint64 `json:"result"`
+}
+
+func (q QueryResNonce) String() string {
+	return string(q.Nonce)
+}