Impove test coverage of x/evm/statedb package

Closes: #876
- coverage: 99.3% of statements

x/evm/statedb/access_list.go

@@ -54,23 +54,6 @@ func newAccessList() *accessList {
 	}
 }
 
-// Copy creates an independent copy of an accessList.
-func (al *accessList) Copy() *accessList {
-	cp := newAccessList()
-	for k, v := range al.addresses {
-		cp.addresses[k] = v
-	}
-	cp.slots = make([]map[common.Hash]struct{}, len(al.slots))
-	for i, slotMap := range al.slots {
-		newSlotmap := make(map[common.Hash]struct{}, len(slotMap))
-		for k := range slotMap {
-			newSlotmap[k] = struct{}{}
-		}
-		cp.slots[i] = newSlotmap
-	}
-	return cp
-}
-
 // AddAddress adds an address to the access list, and returns 'true' if the operation
 // caused a change (addr was not previously in the list).
 func (al *accessList) AddAddress(address common.Address) bool {

x/evm/statedb/mock_test.go

@@ -1,29 +1,35 @@
 package statedb_test
 
 import (
+	"bytes"
+	"errors"
 	"math/big"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/tharsis/ethermint/x/evm/statedb"
 )
 
-var _ statedb.Keeper = &MockKeeper{}
+var (
+	_             statedb.Keeper = &MockKeeper{}
+	errAddress    common.Address = common.BigToAddress(big.NewInt(100))
+	emptyCodeHash                = crypto.Keccak256(nil)
+)
 
-type MockKeeper struct {
-	errAddress common.Address
+type MockAcount struct {
+	account statedb.Account
+	states  statedb.Storage
+}
 
-	accounts map[common.Address]statedb.Account
-	states   map[common.Address]statedb.Storage
+type MockKeeper struct {
+	accounts map[common.Address]MockAcount
 	codes    map[common.Hash][]byte
 }
 
 func NewMockKeeper() *MockKeeper {
 	return &MockKeeper{
-		errAddress: common.BigToAddress(big.NewInt(1)),
-
-		accounts: make(map[common.Address]statedb.Account),
-		states:   make(map[common.Address]statedb.Storage),
+		accounts: make(map[common.Address]MockAcount),
 		codes:    make(map[common.Hash][]byte),
 	}
 }
@@ -33,35 +39,49 @@ func (k MockKeeper) GetAccount(ctx sdk.Context, addr common.Address) *statedb.Ac
 	if !ok {
 		return nil
 	}
-	return &acct
+	return &acct.account
 }
 
 func (k MockKeeper) GetState(ctx sdk.Context, addr common.Address, key common.Hash) common.Hash {
-	return k.states[addr][key]
+	return k.accounts[addr].states[key]
 }
 
 func (k MockKeeper) GetCode(ctx sdk.Context, codeHash common.Hash) []byte {
 	return k.codes[codeHash]
 }
 
 func (k MockKeeper) ForEachStorage(ctx sdk.Context, addr common.Address, cb func(key, value common.Hash) bool) {
-	for k, v := range k.states[addr] {
-		if !cb(k, v) {
-			return
+	if acct, ok := k.accounts[addr]; ok {
+		for k, v := range acct.states {
+			if !cb(k, v) {
+				return
+			}
 		}
 	}
 }
 
 func (k MockKeeper) SetAccount(ctx sdk.Context, addr common.Address, account statedb.Account) error {
-	k.accounts[addr] = account
+	if addr == errAddress {
+		return errors.New("mock db error")
+	}
+	acct, exists := k.accounts[addr]
+	if exists {
+		// update
+		acct.account = account
+		k.accounts[addr] = acct
+	} else {
+		k.accounts[addr] = MockAcount{account: account, states: make(statedb.Storage)}
+	}
 	return nil
 }
 
 func (k MockKeeper) SetState(ctx sdk.Context, addr common.Address, key common.Hash, value []byte) {
-	if len(value) == 0 {
-		delete(k.states[addr], key)
-	} else {
-		k.states[addr][key] = common.BytesToHash(value)
+	if acct, ok := k.accounts[addr]; ok {
+		if len(value) == 0 {
+			delete(acct.states, key)
+		} else {
+			acct.states[key] = common.BytesToHash(value)
+		}
 	}
 }
 
@@ -70,11 +90,25 @@ func (k MockKeeper) SetCode(ctx sdk.Context, codeHash []byte, code []byte) {
 }
 
 func (k MockKeeper) DeleteAccount(ctx sdk.Context, addr common.Address) error {
+	if addr == errAddress {
+		return errors.New("mock db error")
+	}
 	old := k.accounts[addr]
 	delete(k.accounts, addr)
-	delete(k.states, addr)
-	if len(old.CodeHash) > 0 {
-		delete(k.codes, common.BytesToHash(old.CodeHash))
+	if !bytes.Equal(old.account.CodeHash, emptyCodeHash) {
+		delete(k.codes, common.BytesToHash(old.account.CodeHash))
 	}
 	return nil
 }
+
+func (k MockKeeper) Clone() *MockKeeper {
+	accounts := make(map[common.Address]MockAcount, len(k.accounts))
+	for k, v := range k.accounts {
+		accounts[k] = v
+	}
+	codes := make(map[common.Hash][]byte, len(k.codes))
+	for k, v := range k.codes {
+		codes[k] = v
+	}
+	return &MockKeeper{accounts, codes}
+}

x/evm/statedb/state_object.go

@@ -124,9 +124,6 @@ func (s *stateObject) setBalance(amount *big.Int) {
 	s.account.Balance = amount
 }
 
-// Return the gas back to the origin. Used by the Virtual machine or Closures
-func (s *stateObject) ReturnGas(gas *big.Int) {}
-
 //
 // Attribute accessors
 //

x/evm/statedb/statedb.go

@@ -70,11 +70,6 @@ func (s *StateDB) Keeper() Keeper {
 	return s.keeper
 }
 
-// Context returns the embedded `sdk.Context`
-func (s *StateDB) Context() sdk.Context {
-	return s.ctx
-}
-
 // AddLog adds a log, called by evm.
 func (s *StateDB) AddLog(log *ethtypes.Log) {
 	s.journal.append(addLogChange{})
@@ -139,16 +134,6 @@ func (s *StateDB) GetNonce(addr common.Address) uint64 {
 	return 0
 }
 
-// TxIndex returns the current transaction index.
-func (s *StateDB) TxIndex() uint {
-	return s.txConfig.TxIndex
-}
-
-// BlockHash returns the current block hash.
-func (s *StateDB) BlockHash() common.Hash {
-	return s.txConfig.BlockHash
-}
-
 // GetCode returns the code of account, nil if not exists.
 func (s *StateDB) GetCode(addr common.Address) []byte {
 	stateObject := s.getStateObject(addr)