diff --git a/core/blockchain_test.go b/core/blockchain_test.go index 748cdc5c71..375823b57b 100644 --- a/core/blockchain_test.go +++ b/core/blockchain_test.go @@ -1338,3 +1338,114 @@ func TestLargeReorgTrieGC(t *testing.T) { } } } + +// Benchmarks large blocks with value transfers to non-existing accounts +func benchmarkLargeNumberOfValueToNonexisting(b *testing.B, numTxs, numBlocks int, recipientFn func(uint64) common.Address, dataFn func(uint64) []byte) { + var ( + signer = types.HomesteadSigner{} + testBankKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291") + testBankAddress = crypto.PubkeyToAddress(testBankKey.PublicKey) + bankFunds = big.NewInt(100000000000000000) + gspec = Genesis{ + Config: params.TestChainConfig, + Alloc: GenesisAlloc{ + testBankAddress: {Balance: bankFunds}, + common.HexToAddress("0xc0de"): { + Code: []byte{0x60, 0x01, 0x50}, + Balance: big.NewInt(0), + }, // push 1, pop + }, + GasLimit: 100e6, // 100 M + } + ) + // Generate the original common chain segment and the two competing forks + engine := ethash.NewFaker() + db, _ := ethdb.NewMemDatabase() + genesis := gspec.MustCommit(db) + + blockGenerator := func(i int, block *BlockGen) { + block.SetCoinbase(common.Address{1}) + for txi := 0; txi < numTxs; txi++ { + uniq := uint64(i*numTxs + txi) + recipient := recipientFn(uniq) + //recipient := common.BigToAddress(big.NewInt(0).SetUint64(1337 + uniq)) + tx, err := types.SignTx(types.NewTransaction(uniq, recipient, big.NewInt(1), params.TxGas, big.NewInt(1), nil), signer, testBankKey) + if err != nil { + b.Error(err) + } + block.AddTx(tx) + } + } + + shared, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, numBlocks, blockGenerator) + b.StopTimer() + b.ResetTimer() + for i := 0; i < b.N; i++ { + // Import the shared chain and the original canonical one + diskdb, _ := ethdb.NewMemDatabase() + gspec.MustCommit(diskdb) + + chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}) + if err != nil { + b.Fatalf("failed to create tester chain: %v", err) + } + b.StartTimer() + if _, err := chain.InsertChain(shared); err != nil { + b.Fatalf("failed to insert shared chain: %v", err) + } + b.StopTimer() + if got := chain.CurrentBlock().Transactions().Len(); got != numTxs*numBlocks { + b.Fatalf("Transactions were not included, expected %d, got %d", (numTxs * numBlocks), got) + + } + } +} +func BenchmarkBlockChain_1x1000ValueTransferToNonexisting(b *testing.B) { + var ( + numTxs = 1000 + numBlocks = 1 + ) + + recipientFn := func(nonce uint64) common.Address { + return common.BigToAddress(big.NewInt(0).SetUint64(1337 + nonce)) + } + dataFn := func(nonce uint64) []byte { + return nil + } + + benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn) +} +func BenchmarkBlockChain_1x1000ValueTransferToExisting(b *testing.B) { + var ( + numTxs = 1000 + numBlocks = 1 + ) + b.StopTimer() + b.ResetTimer() + + recipientFn := func(nonce uint64) common.Address { + return common.BigToAddress(big.NewInt(0).SetUint64(1337)) + } + dataFn := func(nonce uint64) []byte { + return nil + } + + benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn) +} +func BenchmarkBlockChain_1x1000Executions(b *testing.B) { + var ( + numTxs = 1000 + numBlocks = 1 + ) + b.StopTimer() + b.ResetTimer() + + recipientFn := func(nonce uint64) common.Address { + return common.BigToAddress(big.NewInt(0).SetUint64(0xc0de)) + } + dataFn := func(nonce uint64) []byte { + return nil + } + + benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn) +} diff --git a/core/state/dump.go b/core/state/dump.go index 46e612850a..072dbbf053 100644 --- a/core/state/dump.go +++ b/core/state/dump.go @@ -53,7 +53,7 @@ func (self *StateDB) RawDump() Dump { panic(err) } - obj := newObject(nil, common.BytesToAddress(addr), data, nil) + obj := newObject(nil, common.BytesToAddress(addr), data) account := DumpAccount{ Balance: data.Balance.String(), Nonce: data.Nonce, diff --git a/core/state/journal.go b/core/state/journal.go index a89bb3d13a..a03ca57dbc 100644 --- a/core/state/journal.go +++ b/core/state/journal.go @@ -22,11 +22,67 @@ import ( "github.com/ethereum/go-ethereum/common" ) +// journalEntry is a modification entry in the state change journal that can be +// reverted on demand. type journalEntry interface { - undo(*StateDB) + // revert undoes the changes introduced by this journal entry. + revert(*StateDB) + + // dirtied returns the Ethereum address modified by this journal entry. + dirtied() *common.Address +} + +// journal contains the list of state modifications applied since the last state +// commit. These are tracked to be able to be reverted in case of an execution +// exception or revertal request. +type journal struct { + entries []journalEntry // Current changes tracked by the journal + dirties map[common.Address]int // Dirty accounts and the number of changes +} + +// newJournal create a new initialized journal. +func newJournal() *journal { + return &journal{ + dirties: make(map[common.Address]int), + } +} + +// append inserts a new modification entry to the end of the change journal. +func (j *journal) append(entry journalEntry) { + j.entries = append(j.entries, entry) + if addr := entry.dirtied(); addr != nil { + j.dirties[*addr]++ + } +} + +// revert undoes a batch of journalled modifications along with any reverted +// dirty handling too. +func (j *journal) revert(statedb *StateDB, snapshot int) { + for i := len(j.entries) - 1; i >= snapshot; i-- { + // Undo the changes made by the operation + j.entries[i].revert(statedb) + + // Drop any dirty tracking induced by the change + if addr := j.entries[i].dirtied(); addr != nil { + if j.dirties[*addr]--; j.dirties[*addr] == 0 { + delete(j.dirties, *addr) + } + } + } + j.entries = j.entries[:snapshot] +} + +// dirty explicitly sets an address to dirty, even if the change entries would +// otherwise suggest it as clean. This method is an ugly hack to handle the RIPEMD +// precompile consensus exception. +func (j *journal) dirty(addr common.Address) { + j.dirties[addr]++ } -type journal []journalEntry +// length returns the current number of entries in the journal. +func (j *journal) length() int { + return len(j.entries) +} type ( // Changes to the account trie. @@ -77,16 +133,24 @@ type ( } ) -func (ch createObjectChange) undo(s *StateDB) { +func (ch createObjectChange) revert(s *StateDB) { delete(s.stateObjects, *ch.account) delete(s.stateObjectsDirty, *ch.account) } -func (ch resetObjectChange) undo(s *StateDB) { +func (ch createObjectChange) dirtied() *common.Address { + return ch.account +} + +func (ch resetObjectChange) revert(s *StateDB) { s.setStateObject(ch.prev) } -func (ch suicideChange) undo(s *StateDB) { +func (ch resetObjectChange) dirtied() *common.Address { + return nil +} + +func (ch suicideChange) revert(s *StateDB) { obj := s.getStateObject(*ch.account) if obj != nil { obj.suicided = ch.prev @@ -94,38 +158,60 @@ func (ch suicideChange) undo(s *StateDB) { } } +func (ch suicideChange) dirtied() *common.Address { + return ch.account +} + var ripemd = common.HexToAddress("0000000000000000000000000000000000000003") -func (ch touchChange) undo(s *StateDB) { - if !ch.prev && *ch.account != ripemd { - s.getStateObject(*ch.account).touched = ch.prev - if !ch.prevDirty { - delete(s.stateObjectsDirty, *ch.account) - } - } +func (ch touchChange) revert(s *StateDB) { +} + +func (ch touchChange) dirtied() *common.Address { + return ch.account } -func (ch balanceChange) undo(s *StateDB) { +func (ch balanceChange) revert(s *StateDB) { s.getStateObject(*ch.account).setBalance(ch.prev) } -func (ch nonceChange) undo(s *StateDB) { +func (ch balanceChange) dirtied() *common.Address { + return ch.account +} + +func (ch nonceChange) revert(s *StateDB) { s.getStateObject(*ch.account).setNonce(ch.prev) } -func (ch codeChange) undo(s *StateDB) { +func (ch nonceChange) dirtied() *common.Address { + return ch.account +} + +func (ch codeChange) revert(s *StateDB) { s.getStateObject(*ch.account).setCode(common.BytesToHash(ch.prevhash), ch.prevcode) } -func (ch storageChange) undo(s *StateDB) { +func (ch codeChange) dirtied() *common.Address { + return ch.account +} + +func (ch storageChange) revert(s *StateDB) { s.getStateObject(*ch.account).setState(ch.key, ch.prevalue) } -func (ch refundChange) undo(s *StateDB) { +func (ch storageChange) dirtied() *common.Address { + return ch.account +} + +func (ch refundChange) revert(s *StateDB) { s.refund = ch.prev } -func (ch addLogChange) undo(s *StateDB) { +func (ch refundChange) dirtied() *common.Address { + return nil +} + +func (ch addLogChange) revert(s *StateDB) { logs := s.logs[ch.txhash] if len(logs) == 1 { delete(s.logs, ch.txhash) @@ -135,6 +221,14 @@ func (ch addLogChange) undo(s *StateDB) { s.logSize-- } -func (ch addPreimageChange) undo(s *StateDB) { +func (ch addLogChange) dirtied() *common.Address { + return nil +} + +func (ch addPreimageChange) revert(s *StateDB) { delete(s.preimages, ch.hash) } + +func (ch addPreimageChange) dirtied() *common.Address { + return nil +} diff --git a/core/state/state_object.go b/core/state/state_object.go index b2112bfaec..3c40c20415 100644 --- a/core/state/state_object.go +++ b/core/state/state_object.go @@ -85,9 +85,7 @@ type stateObject struct { // during the "update" phase of the state transition. dirtyCode bool // true if the code was updated suicided bool - touched bool deleted bool - onDirty func(addr common.Address) // Callback method to mark a state object newly dirty } // empty returns whether the account is considered empty. @@ -105,7 +103,7 @@ type Account struct { } // newObject creates a state object. -func newObject(db *StateDB, address common.Address, data Account, onDirty func(addr common.Address)) *stateObject { +func newObject(db *StateDB, address common.Address, data Account) *stateObject { if data.Balance == nil { data.Balance = new(big.Int) } @@ -119,7 +117,6 @@ func newObject(db *StateDB, address common.Address, data Account, onDirty func(a data: data, cachedStorage: make(Storage), dirtyStorage: make(Storage), - onDirty: onDirty, } } @@ -137,23 +134,17 @@ func (self *stateObject) setError(err error) { func (self *stateObject) markSuicided() { self.suicided = true - if self.onDirty != nil { - self.onDirty(self.Address()) - self.onDirty = nil - } } func (c *stateObject) touch() { - c.db.journal = append(c.db.journal, touchChange{ - account: &c.address, - prev: c.touched, - prevDirty: c.onDirty == nil, + c.db.journal.append(touchChange{ + account: &c.address, }) - if c.onDirty != nil { - c.onDirty(c.Address()) - c.onDirty = nil + if c.address == ripemd { + // Explicitly put it in the dirty-cache, which is otherwise generated from + // flattened journals. + c.db.journal.dirty(c.address) } - c.touched = true } func (c *stateObject) getTrie(db Database) Trie { @@ -195,7 +186,7 @@ func (self *stateObject) GetState(db Database, key common.Hash) common.Hash { // SetState updates a value in account storage. func (self *stateObject) SetState(db Database, key, value common.Hash) { - self.db.journal = append(self.db.journal, storageChange{ + self.db.journal.append(storageChange{ account: &self.address, key: key, prevalue: self.GetState(db, key), @@ -207,10 +198,6 @@ func (self *stateObject) setState(key, value common.Hash) { self.cachedStorage[key] = value self.dirtyStorage[key] = value - if self.onDirty != nil { - self.onDirty(self.Address()) - self.onDirty = nil - } } // updateTrie writes cached storage modifications into the object's storage trie. @@ -274,7 +261,7 @@ func (c *stateObject) SubBalance(amount *big.Int) { } func (self *stateObject) SetBalance(amount *big.Int) { - self.db.journal = append(self.db.journal, balanceChange{ + self.db.journal.append(balanceChange{ account: &self.address, prev: new(big.Int).Set(self.data.Balance), }) @@ -283,17 +270,13 @@ func (self *stateObject) SetBalance(amount *big.Int) { func (self *stateObject) setBalance(amount *big.Int) { self.data.Balance = amount - if self.onDirty != nil { - self.onDirty(self.Address()) - self.onDirty = nil - } } // Return the gas back to the origin. Used by the Virtual machine or Closures func (c *stateObject) ReturnGas(gas *big.Int) {} -func (self *stateObject) deepCopy(db *StateDB, onDirty func(addr common.Address)) *stateObject { - stateObject := newObject(db, self.address, self.data, onDirty) +func (self *stateObject) deepCopy(db *StateDB) *stateObject { + stateObject := newObject(db, self.address, self.data) if self.trie != nil { stateObject.trie = db.db.CopyTrie(self.trie) } @@ -333,7 +316,7 @@ func (self *stateObject) Code(db Database) []byte { func (self *stateObject) SetCode(codeHash common.Hash, code []byte) { prevcode := self.Code(self.db.db) - self.db.journal = append(self.db.journal, codeChange{ + self.db.journal.append(codeChange{ account: &self.address, prevhash: self.CodeHash(), prevcode: prevcode, @@ -345,14 +328,10 @@ func (self *stateObject) setCode(codeHash common.Hash, code []byte) { self.code = code self.data.CodeHash = codeHash[:] self.dirtyCode = true - if self.onDirty != nil { - self.onDirty(self.Address()) - self.onDirty = nil - } } func (self *stateObject) SetNonce(nonce uint64) { - self.db.journal = append(self.db.journal, nonceChange{ + self.db.journal.append(nonceChange{ account: &self.address, prev: self.data.Nonce, }) @@ -361,10 +340,6 @@ func (self *stateObject) SetNonce(nonce uint64) { func (self *stateObject) setNonce(nonce uint64) { self.data.Nonce = nonce - if self.onDirty != nil { - self.onDirty(self.Address()) - self.onDirty = nil - } } func (self *stateObject) CodeHash() []byte { diff --git a/core/state/statedb.go b/core/state/statedb.go index bd67e789d5..08f18c2d2f 100644 --- a/core/state/statedb.go +++ b/core/state/statedb.go @@ -76,7 +76,7 @@ type StateDB struct { // Journal of state modifications. This is the backbone of // Snapshot and RevertToSnapshot. - journal journal + journal *journal validRevisions []revision nextRevisionId int @@ -96,6 +96,7 @@ func New(root common.Hash, db Database) (*StateDB, error) { stateObjectsDirty: make(map[common.Address]struct{}), logs: make(map[common.Hash][]*types.Log), preimages: make(map[common.Hash][]byte), + journal: newJournal(), }, nil } @@ -131,7 +132,7 @@ func (self *StateDB) Reset(root common.Hash) error { } func (self *StateDB) AddLog(log *types.Log) { - self.journal = append(self.journal, addLogChange{txhash: self.thash}) + self.journal.append(addLogChange{txhash: self.thash}) log.TxHash = self.thash log.BlockHash = self.bhash @@ -156,7 +157,7 @@ func (self *StateDB) Logs() []*types.Log { // AddPreimage records a SHA3 preimage seen by the VM. func (self *StateDB) AddPreimage(hash common.Hash, preimage []byte) { if _, ok := self.preimages[hash]; !ok { - self.journal = append(self.journal, addPreimageChange{hash: hash}) + self.journal.append(addPreimageChange{hash: hash}) pi := make([]byte, len(preimage)) copy(pi, preimage) self.preimages[hash] = pi @@ -169,7 +170,7 @@ func (self *StateDB) Preimages() map[common.Hash][]byte { } func (self *StateDB) AddRefund(gas uint64) { - self.journal = append(self.journal, refundChange{prev: self.refund}) + self.journal.append(refundChange{prev: self.refund}) self.refund += gas } @@ -255,7 +256,7 @@ func (self *StateDB) StorageTrie(addr common.Address) Trie { if stateObject == nil { return nil } - cpy := stateObject.deepCopy(self, nil) + cpy := stateObject.deepCopy(self) return cpy.updateTrie(self.db) } @@ -325,7 +326,7 @@ func (self *StateDB) Suicide(addr common.Address) bool { if stateObject == nil { return false } - self.journal = append(self.journal, suicideChange{ + self.journal.append(suicideChange{ account: &addr, prev: stateObject.suicided, prevbalance: new(big.Int).Set(stateObject.Balance()), @@ -379,7 +380,7 @@ func (self *StateDB) getStateObject(addr common.Address) (stateObject *stateObje return nil } // Insert into the live set. - obj := newObject(self, addr, data, self.MarkStateObjectDirty) + obj := newObject(self, addr, data) self.setStateObject(obj) return obj } @@ -397,22 +398,16 @@ func (self *StateDB) GetOrNewStateObject(addr common.Address) *stateObject { return stateObject } -// MarkStateObjectDirty adds the specified object to the dirty map to avoid costly -// state object cache iteration to find a handful of modified ones. -func (self *StateDB) MarkStateObjectDirty(addr common.Address) { - self.stateObjectsDirty[addr] = struct{}{} -} - // createObject creates a new state object. If there is an existing account with // the given address, it is overwritten and returned as the second return value. func (self *StateDB) createObject(addr common.Address) (newobj, prev *stateObject) { prev = self.getStateObject(addr) - newobj = newObject(self, addr, Account{}, self.MarkStateObjectDirty) + newobj = newObject(self, addr, Account{}) newobj.setNonce(0) // sets the object to dirty if prev == nil { - self.journal = append(self.journal, createObjectChange{account: &addr}) + self.journal.append(createObjectChange{account: &addr}) } else { - self.journal = append(self.journal, resetObjectChange{prev: prev}) + self.journal.append(resetObjectChange{prev: prev}) } self.setStateObject(newobj) return newobj, prev @@ -466,16 +461,17 @@ func (self *StateDB) Copy() *StateDB { state := &StateDB{ db: self.db, trie: self.db.CopyTrie(self.trie), - stateObjects: make(map[common.Address]*stateObject, len(self.stateObjectsDirty)), - stateObjectsDirty: make(map[common.Address]struct{}, len(self.stateObjectsDirty)), + stateObjects: make(map[common.Address]*stateObject, len(self.journal.dirties)), + stateObjectsDirty: make(map[common.Address]struct{}, len(self.journal.dirties)), refund: self.refund, logs: make(map[common.Hash][]*types.Log, len(self.logs)), logSize: self.logSize, preimages: make(map[common.Hash][]byte), + journal: newJournal(), } // Copy the dirty states, logs, and preimages - for addr := range self.stateObjectsDirty { - state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state, state.MarkStateObjectDirty) + for addr := range self.journal.dirties { + state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state) state.stateObjectsDirty[addr] = struct{}{} } for hash, logs := range self.logs { @@ -492,7 +488,7 @@ func (self *StateDB) Copy() *StateDB { func (self *StateDB) Snapshot() int { id := self.nextRevisionId self.nextRevisionId++ - self.validRevisions = append(self.validRevisions, revision{id, len(self.journal)}) + self.validRevisions = append(self.validRevisions, revision{id, self.journal.length()}) return id } @@ -507,13 +503,8 @@ func (self *StateDB) RevertToSnapshot(revid int) { } snapshot := self.validRevisions[idx].journalIndex - // Replay the journal to undo changes. - for i := len(self.journal) - 1; i >= snapshot; i-- { - self.journal[i].undo(self) - } - self.journal = self.journal[:snapshot] - - // Remove invalidated snapshots from the stack. + // Replay the journal to undo changes and remove invalidated snapshots + self.journal.revert(self, snapshot) self.validRevisions = self.validRevisions[:idx] } @@ -525,14 +516,25 @@ func (self *StateDB) GetRefund() uint64 { // Finalise finalises the state by removing the self destructed objects // and clears the journal as well as the refunds. func (s *StateDB) Finalise(deleteEmptyObjects bool) { - for addr := range s.stateObjectsDirty { - stateObject := s.stateObjects[addr] + for addr := range s.journal.dirties { + stateObject, exist := s.stateObjects[addr] + if !exist { + // ripeMD is 'touched' at block 1714175, in tx 0x1237f737031e40bcde4a8b7e717b2d15e3ecadfe49bb1bbc71ee9deb09c6fcf2 + // That tx goes out of gas, and although the notion of 'touched' does not exist there, the + // touch-event will still be recorded in the journal. Since ripeMD is a special snowflake, + // it will persist in the journal even though the journal is reverted. In this special circumstance, + // it may exist in `s.journal.dirties` but not in `s.stateObjects`. + // Thus, we can safely ignore it here + continue + } + if stateObject.suicided || (deleteEmptyObjects && stateObject.empty()) { s.deleteStateObject(stateObject) } else { stateObject.updateRoot(s.db) s.updateStateObject(stateObject) } + s.stateObjectsDirty[addr] = struct{}{} } // Invalidate journal because reverting across transactions is not allowed. s.clearJournalAndRefund() @@ -576,7 +578,7 @@ func (s *StateDB) DeleteSuicides() { } func (s *StateDB) clearJournalAndRefund() { - s.journal = nil + s.journal = newJournal() s.validRevisions = s.validRevisions[:0] s.refund = 0 } @@ -585,6 +587,9 @@ func (s *StateDB) clearJournalAndRefund() { func (s *StateDB) Commit(deleteEmptyObjects bool) (root common.Hash, err error) { defer s.clearJournalAndRefund() + for addr := range s.journal.dirties { + s.stateObjectsDirty[addr] = struct{}{} + } // Commit objects to the trie. for addr, stateObject := range s.stateObjects { _, isDirty := s.stateObjectsDirty[addr] diff --git a/core/state/statedb_test.go b/core/state/statedb_test.go index d9e3d9b797..340c840f13 100644 --- a/core/state/statedb_test.go +++ b/core/state/statedb_test.go @@ -413,11 +413,12 @@ func (s *StateSuite) TestTouchDelete(c *check.C) { snapshot := s.state.Snapshot() s.state.AddBalance(common.Address{}, new(big.Int)) - if len(s.state.stateObjectsDirty) != 1 { + + if len(s.state.journal.dirties) != 1 { c.Fatal("expected one dirty state object") } s.state.RevertToSnapshot(snapshot) - if len(s.state.stateObjectsDirty) != 0 { + if len(s.state.journal.dirties) != 0 { c.Fatal("expected no dirty state object") } } diff --git a/tests/state_test.go b/tests/state_test.go index 9ca5f18303..3fd3ce43ab 100644 --- a/tests/state_test.go +++ b/tests/state_test.go @@ -36,14 +36,8 @@ func TestState(t *testing.T) { st.skipLoad(`^stTransactionTest/zeroSigTransa[^/]*\.json`) // EIP-86 is not supported yet // Expected failures: st.fails(`^stRevertTest/RevertPrecompiledTouch\.json/EIP158`, "bug in test") - st.fails(`^stRevertTest/RevertPrefoundEmptyOOG\.json/EIP158`, "bug in test") st.fails(`^stRevertTest/RevertPrecompiledTouch\.json/Byzantium`, "bug in test") - st.fails(`^stRevertTest/RevertPrefoundEmptyOOG\.json/Byzantium`, "bug in test") st.fails(`^stRandom2/randomStatetest64[45]\.json/(EIP150|Frontier|Homestead)/.*`, "known bug #15119") - st.fails(`^stCreateTest/TransactionCollisionToEmpty\.json/EIP158/2`, "known bug ") - st.fails(`^stCreateTest/TransactionCollisionToEmpty\.json/EIP158/3`, "known bug ") - st.fails(`^stCreateTest/TransactionCollisionToEmpty\.json/Byzantium/2`, "known bug ") - st.fails(`^stCreateTest/TransactionCollisionToEmpty\.json/Byzantium/3`, "known bug ") st.walk(t, stateTestDir, func(t *testing.T, name string, test *StateTest) { for _, subtest := range test.Subtests() {