1 files changed, 184 insertions, 0 deletions
diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
new file mode 100644
index 000000000..17a0ed7fe
--- /dev/null
+++ b/accounts/abi/bind/backends/simulated.go
@@ -0,0 +1,184 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package backends
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
+)
+
+// SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
+// the background. Its main purpose is to allow easily testing contract bindings.
+type SimulatedBackend struct {
+	database   ethdb.Database   // In memory database to store our testing data
+	blockchain *core.BlockChain // Ethereum blockchain to handle the consensus
+
+	pendingBlock *types.Block   // Currently pending block that will be imported on request
+	pendingState *state.StateDB // Currently pending state that will be the active on on request
+}
+
+// NewSimulatedBackend creates a new binding backend using a simulated blockchain
+// for testing purposes.
+func NewSimulatedBackend(accounts ...core.GenesisAccount) *SimulatedBackend {
+	database, _ := ethdb.NewMemDatabase()
+	core.WriteGenesisBlockForTesting(database, accounts...)
+	blockchain, _ := core.NewBlockChain(database, new(core.FakePow), new(event.TypeMux))
+
+	backend := &SimulatedBackend{
+		database:   database,
+		blockchain: blockchain,
+	}
+	backend.Rollback()
+
+	return backend
+}
+
+// Commit imports all the pending transactions as a single block and starts a
+// fresh new state.
+func (b *SimulatedBackend) Commit() {
+	if _, err := b.blockchain.InsertChain([]*types.Block{b.pendingBlock}); err != nil {
+		panic(err) // This cannot happen unless the simulator is wrong, fail in that case
+	}
+	b.Rollback()
+}
+
+// Rollback aborts all pending transactions, reverting to the last committed state.
+func (b *SimulatedBackend) Rollback() {
+	blocks, _ := core.GenerateChain(b.blockchain.CurrentBlock(), b.database, 1, func(int, *core.BlockGen) {})
+
+	b.pendingBlock = blocks[0]
+	b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
+}
+
+// ContractCall implements ContractCaller.ContractCall, executing the specified
+// contract with the given input data.
+func (b *SimulatedBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {
+	// Create a copy of the current state db to screw around with
+	var (
+		block   *types.Block
+		statedb *state.StateDB
+	)
+	if pending {
+		block, statedb = b.pendingBlock, b.pendingState
+	} else {
+		block = b.blockchain.CurrentBlock()
+		statedb, _ = b.blockchain.State()
+	}
+	statedb = statedb.Copy()
+
+	// Set infinite balance to the a fake caller account
+	from := statedb.GetOrNewStateObject(common.Address{})
+	from.SetBalance(common.MaxBig)
+
+	// Assemble the call invocation to measure the gas usage
+	msg := callmsg{
+		from:     from,
+		to:       &contract,
+		gasPrice: new(big.Int),
+		gasLimit: common.MaxBig,
+		value:    new(big.Int),
+		data:     data,
+	}
+	// Execute the call and return
+	vmenv := core.NewEnv(statedb, b.blockchain, msg, block.Header())
+	gaspool := new(core.GasPool).AddGas(common.MaxBig)
+
+	out, _, err := core.ApplyMessage(vmenv, msg, gaspool)
+	return out, err
+}
+
+// AccountNonce implements ContractTransactor.AccountNonce, retrieving the nonce
+// currently pending for the account.
+func (b *SimulatedBackend) AccountNonce(account common.Address) (uint64, error) {
+	return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
+}
+
+// GasPrice implements ContractTransactor.GasPrice. Since the simulated chain
+// doens't have miners, we just return a gas price of 1 for any call.
+func (b *SimulatedBackend) GasPrice() (*big.Int, error) {
+	return big.NewInt(1), nil
+}
+
+// GasLimit implements ContractTransactor.GasLimit, executing the requested code
+// against the currently pending block/state and returning the used gas.
+func (b *SimulatedBackend) GasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
+	// Create a copy of the currently pending state db to screw around with
+	var (
+		block   = b.pendingBlock
+		statedb = b.pendingState.Copy()
+	)
+
+	// Set infinite balance to the a fake caller account
+	from := statedb.GetOrNewStateObject(sender)
+	from.SetBalance(common.MaxBig)
+
+	// Assemble the call invocation to measure the gas usage
+	msg := callmsg{
+		from:     from,
+		to:       contract,
+		gasPrice: new(big.Int),
+		gasLimit: common.MaxBig,
+		value:    value,
+		data:     data,
+	}
+	// Execute the call and return
+	vmenv := core.NewEnv(statedb, b.blockchain, msg, block.Header())
+	gaspool := new(core.GasPool).AddGas(common.MaxBig)
+
+	_, gas, err := core.ApplyMessage(vmenv, msg, gaspool)
+	return gas, err
+}
+
+// Transact implements ContractTransactor.SendTransaction, delegating the raw
+// transaction injection to the remote node.
+func (b *SimulatedBackend) SendTransaction(tx *types.Transaction) error {
+	blocks, _ := core.GenerateChain(b.blockchain.CurrentBlock(), b.database, 1, func(number int, block *core.BlockGen) {
+		for _, tx := range b.pendingBlock.Transactions() {
+			block.AddTx(tx)
+		}
+		block.AddTx(tx)
+	})
+	b.pendingBlock = blocks[0]
+	b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
+
+	return nil
+}
+
+// callmsg implements core.Message to allow passing it as a transaction simulator.
+type callmsg struct {
+	from     *state.StateObject
+	to       *common.Address
+	gasLimit *big.Int
+	gasPrice *big.Int
+	value    *big.Int
+	data     []byte
+}
+
+func (m callmsg) From() (common.Address, error)         { return m.from.Address(), nil }
+func (m callmsg) FromFrontier() (common.Address, error) { return m.from.Address(), nil }
+func (m callmsg) Nonce() uint64                         { return m.from.Nonce() }
+func (m callmsg) To() *common.Address                   { return m.to }
+func (m callmsg) GasPrice() *big.Int                    { return m.gasPrice }
+func (m callmsg) Gas() *big.Int                         { return m.gasLimit }
+func (m callmsg) Value() *big.Int                       { return m.value }
+func (m callmsg) Data() []byte                          { return m.data }