Merge PR: add pending mode for test (#506)

Co-authored-by: MengXiangJian <805442788@qq.com>

app/rpc/backend/backend.go

@@ -22,6 +22,7 @@ import (
 type Backend interface {
 	// Used by block filter; also used for polling
 	BlockNumber() (hexutil.Uint64, error)
+	LatestBlockNumber() (int64, error)
 	HeaderByNumber(blockNum rpctypes.BlockNumber) (*ethtypes.Header, error)
 	HeaderByHash(blockHash common.Hash) (*ethtypes.Header, error)
 	GetBlockByNumber(blockNum rpctypes.BlockNumber, fullTx bool) (map[string]interface{}, error)
@@ -60,13 +61,12 @@ func New(clientCtx clientcontext.CLIContext) *EthermintBackend {
 
 // BlockNumber returns the current block number.
 func (b *EthermintBackend) BlockNumber() (hexutil.Uint64, error) {
-	// NOTE: using 0 as min and max height returns the blockchain info up to the latest block.
-	info, err := b.clientCtx.Client.BlockchainInfo(0, 0)
+	blockNumber, err := b.LatestBlockNumber()
 	if err != nil {
 		return hexutil.Uint64(0), err
 	}
 
-	return hexutil.Uint64(info.LastHeight), nil
+	return hexutil.Uint64(blockNumber), nil
 }
 
 // GetBlockByNumber returns the block identified by number.
@@ -196,7 +196,7 @@ func (b *EthermintBackend) PendingTransactions() ([]*rpctypes.Transaction, error
 		return nil, err
 	}
 
-	transactions := make([]*rpctypes.Transaction, pendingTxs.Count)
+	transactions := make([]*rpctypes.Transaction, 0)
 	for _, tx := range pendingTxs.Txs {
 		ethTx, err := rpctypes.RawTxToEthTx(b.clientCtx, tx)
 		if err != nil {
@@ -257,3 +257,14 @@ func (b *EthermintBackend) GetLogs(blockHash common.Hash) ([][]*ethtypes.Log, er
 func (b *EthermintBackend) BloomStatus() (uint64, uint64) {
 	return 4096, 0
 }
+
+// LatestBlockNumber gets the latest block height in int64 format.
+func (b *EthermintBackend) LatestBlockNumber() (int64, error) {
+	// NOTE: using 0 as min and max height returns the blockchain info up to the latest block.
+	info, err := b.clientCtx.Client.BlockchainInfo(0, 0)
+	if err != nil {
+		return 0, err
+	}
+
+	return info.LastHeight, nil
+}