decouple CreateBlockchain and UTXOPool into different methods

blockchain/block_test.go

@@ -6,8 +6,8 @@ import (
 )
 
 func TestBlockSerialize(t *testing.T) {
-	cbtx, utxoPool := NewCoinbaseTX("minh", genesisCoinbaseData)
+	cbtx := NewCoinbaseTX("minh", genesisCoinbaseData)
-	if cbtx == nil || utxoPool == nil {
+	if cbtx == nil {
 		t.Errorf("Failed to create a coinbase transaction.")
 	}
 	block := NewGenesisBlock(cbtx)

blockchain/blockchain.go

@@ -161,13 +161,13 @@ func (bc *Blockchain) VerifyNewBlockAndUpdate(utxopool *UTXOPool, block *Block)
 }
 
 // CreateBlockchain creates a new blockchain DB
-func CreateBlockchain(address string) (*Blockchain, *UTXOPool) {
+func CreateBlockchain(address string) *Blockchain {
 	// TODO: We assume we have not created any blockchain before.
 	// In current bitcoin, we can check if we created a blockchain before accessing local db.
-	cbtx, utxoPool := NewCoinbaseTX(address, genesisCoinbaseData)
+	cbtx := NewCoinbaseTX(address, genesisCoinbaseData)
 	genesis := NewGenesisBlock(cbtx)
 
 	bc := Blockchain{[]*Block{genesis}}
 
-	return &bc, utxoPool
+	return &bc
 }

blockchain/blockchain_test.go

@@ -5,14 +5,14 @@ import (
 )
 
 func TestCreateBlockchain(t *testing.T) {
-	if bc, _ := CreateBlockchain("minh"); bc == nil {
+	if bc := CreateBlockchain("minh"); bc == nil {
 		t.Errorf("failed to create a blockchain")
 	}
 }
 
 func TestFindSpendableOutputs(t *testing.T) {
 	requestAmount := 3
-	bc, _ := CreateBlockchain("minh")
+	bc := CreateBlockchain("minh")
 	accumulated, unspentOutputs := bc.FindSpendableOutputs("minh", requestAmount)
 	if accumulated < DefaultCoinbaseValue {
 		t.Error("Failed to find enough unspent ouptuts")
@@ -24,7 +24,7 @@ func TestFindSpendableOutputs(t *testing.T) {
 }
 
 func TestFindUTXO(t *testing.T) {
-	bc, _ := CreateBlockchain("minh")
+	bc := CreateBlockchain("minh")
 	utxo := bc.FindUTXO("minh")
 
 	total := 0
@@ -41,7 +41,8 @@ func TestFindUTXO(t *testing.T) {
 }
 
 func TestAddNewUserTransfer(t *testing.T) {
-	bc, utxoPool := CreateBlockchain("minh")
+	bc := CreateBlockchain("minh")
+	utxoPool := CreateUTXOPoolFromGenesisBlockChain(bc)
 
 	if !bc.AddNewUserTransfer(utxoPool, "minh", "alok", 3) {
 		t.Error("Failed to add new transfer to alok.")
@@ -57,7 +58,9 @@ func TestAddNewUserTransfer(t *testing.T) {
 }
 
 func TestVerifyNewBlock(t *testing.T) {
-	bc, utxoPool := CreateBlockchain("minh")
+	bc := CreateBlockchain("minh")
+	utxoPool := CreateUTXOPoolFromGenesisBlockChain(bc)
+
 	bc.AddNewUserTransfer(utxoPool, "minh", "alok", 3)
 	bc.AddNewUserTransfer(utxoPool, "minh", "rj", 100)
 

blockchain/transaction.go

@@ -47,7 +47,7 @@ func (tx *Transaction) SetID() {
 }
 
 // NewCoinbaseTX creates a new coinbase transaction
-func NewCoinbaseTX(to, data string) (*Transaction, *UTXOPool) {
+func NewCoinbaseTX(to, data string) *Transaction {
 	if data == "" {
 		data = fmt.Sprintf("Reward to '%s'", to)
 	}
@@ -56,14 +56,7 @@ func NewCoinbaseTX(to, data string) (*Transaction, *UTXOPool) {
 	txout := TXOutput{DefaultCoinbaseValue, to}
 	tx := Transaction{nil, []TXInput{txin}, []TXOutput{txout}}
 	tx.SetID()
-	txID := hex.EncodeToString(tx.ID)
+	return &tx
-
-	var utxoPool UTXOPool
-	utxoPool.utxo = make(map[string]map[string]int)
-	utxoPool.utxo[to] = make(map[string]int)
-	utxoPool.utxo[to][txID] = DefaultCoinbaseValue
-
-	return &tx, &utxoPool
 }
 
 // Used for debuging.

blockchain/transaction_test.go

@@ -5,7 +5,7 @@ import (
 )
 
 func TestNewCoinbaseTX(t *testing.T) {
-	if cbtx, utxoPool := NewCoinbaseTX("minh", genesisCoinbaseData); cbtx == nil || utxoPool == nil {
+	if cbtx := NewCoinbaseTX("minh", genesisCoinbaseData); cbtx == nil {
 		t.Errorf("failed to create a coinbase transaction.")
 	}
 }

blockchain/utxopool.go

@@ -6,9 +6,9 @@ import (
 
 // UTXOPool stores transactions and balance associated with each address.
 type UTXOPool struct {
-	// Mapping from address to a map of transaction id to that balance.
+	// Mapping from address to a map of transaction id to a map of the index of output
-	// The assumption here is that one address only appears once output array in a transaction.
+	// array in that transaction to that balance.
-	utxo map[string]map[string]map[int]int
+	utxo map[string]map[string]int
 }
 
 // VerifyTransactions verifies if a list of transactions valid.
@@ -88,3 +88,28 @@ func (utxopool *UTXOPool) Update(transactions []*Transaction) {
 		}
 	}
 }
+
+// CreateUTXOPoolFromTransaction a utxo pool from a genesis transaction.
+func CreateUTXOPoolFromTransaction(tx *Transaction) *UTXOPool {
+	var utxoPool UTXOPool
+	txID := hex.EncodeToString(tx.ID)
+	utxoPool.utxo = make(map[string]map[string]int)
+	for _, out := range tx.TxOutput {
+		utxoPool.utxo[out.Address] = make(map[string]int)
+		utxoPool.utxo[out.Address][txID] = DefaultCoinbaseValue
+	}
+	return &utxoPool
+}
+
+// CreateUTXOPoolFromGenesisBlockChain a utxo pool from a genesis blockchain.
+func CreateUTXOPoolFromGenesisBlockChain(bc *Blockchain) *UTXOPool {
+	tx := bc.blocks[0].Transactions[0]
+	var utxoPool UTXOPool
+	txID := hex.EncodeToString(tx.ID)
+	utxoPool.utxo = make(map[string]map[string]int)
+	for _, out := range tx.TxOutput {
+		utxoPool.utxo[out.Address] = make(map[string]int)
+		utxoPool.utxo[out.Address][txID] = DefaultCoinbaseValue
+	}
+	return &utxoPool
+}

blockchain/utxopool_test.go

@@ -5,7 +5,7 @@ import (
 )
 
 func TestVerifyTransactions(t *testing.T) {
-	if cbtx, utxoPool := NewCoinbaseTX("minh", genesisCoinbaseData); cbtx == nil || utxoPool == nil {
+	if cbtx := NewCoinbaseTX("minh", genesisCoinbaseData); cbtx == nil {
 		t.Errorf("failed to create a coinbase transaction.")
 	}
 }