add VerifyNewBlock and its test

blockchain/block.go

@@ -62,7 +62,7 @@ func (b *Block) HashTransactions() []byte {
 	return txHash[:]
 }
 
-// NewBlock creates and returns Block.
+// NewBlock creates and returns a neew block.
 func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
 	block := &Block{time.Now().Unix(), transactions, prevBlockHash, []byte{}}
 	block.Hash = block.HashTransactions()

blockchain/blockchain.go

@@ -1,7 +1,9 @@
 package blockchain
 
 import (
+	"bytes"
 	"encoding/hex"
+	"fmt"
 )
 
 // Blockchain keeps a sequence of Blocks
@@ -134,13 +136,28 @@ func (bc *Blockchain) NewUTXOTransaction(from, to string, amount int) *Transacti
 func (bc *Blockchain) AddNewTransferAmount(from, to string, amount int) *Blockchain {
 	tx := bc.NewUTXOTransaction(from, to, amount)
 	if tx != nil {
-		newBlock := NewBlock([]*Transaction{tx}, bc.blocks[len(bc.blocks)-1].PrevBlockHash)
+		newBlock := NewBlock([]*Transaction{tx}, bc.blocks[len(bc.blocks)-1].Hash)
 		bc.blocks = append(bc.blocks, newBlock)
 		return bc
 	}
 	return nil
 }
 
+// VerifyNewBlock verifies if the new coming block is valid for the current blockchain.
+func (bc *Blockchain) VerifyNewBlock(block *Block) bool {
+	length := len(bc.blocks)
+	if bytes.Compare(block.PrevBlockHash, bc.blocks[length-1].Hash) != 0 {
+		fmt.Println("MINh1")
+		return false
+	}
+	if block.Timestamp < bc.blocks[length-1].Timestamp {
+		fmt.Println("MINh2")
+		return false
+	}
+	// TODO(minhdoan): Check Transactions parts
+	return true
+}
+
 // CreateBlockchain creates a new blockchain DB
 func CreateBlockchain(address string) *Blockchain {
 	// TODO: We assume we have not created any blockchain before.

blockchain/blockchain_test.go

@@ -61,3 +61,19 @@ func TestAddNewTransferAmount(t *testing.T) {
 		t.Error("minh should not have enough fun to make the transfer")
 	}
 }
+
+func TestVerifyNewBlock(t *testing.T) {
+	bc := CreateBlockchain("minh")
+	bc = bc.AddNewTransferAmount("minh", "alok", 3)
+	bc = bc.AddNewTransferAmount("minh", "rj", 100)
+
+	tx := bc.NewUTXOTransaction("minh", "mark", 10)
+	if tx == nil {
+		t.Error("failed to create a new transaction.")
+	}
+	newBlock := NewBlock([]*Transaction{tx}, bc.blocks[len(bc.blocks)-1].Hash)
+
+	if !bc.VerifyNewBlock(newBlock) {
+		t.Error("failed to add a new valid block.")
+	}
+}