Override install phase in travis

Add tests

.travis.yml

@@ -3,7 +3,8 @@ sudo: false
 go:
   - 1.7
 before_install:
-  - bash scripts/install_glide.sh
   - go get github.com/mattn/goveralls
+install:
+  - bash scripts/install_glide.sh
 script:
   - $HOME/gopath/bin/goveralls -service=travis-ci

blockchain/block_test.go

@@ -0,0 +1,20 @@
+package blockchain
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestEncodeBlock(t *testing.T) {
+	b1 := newBlock()
+	b2 := Block{}
+
+	buf := bytes.NewBuffer(make([]byte, 0, b1.Len()))
+
+	b1.Encode(buf)
+	b2.Decode(buf)
+
+	if b1.Hash() != b2.Hash() {
+		t.Fail()
+	}
+}

blockchain/test_utils.go

@@ -0,0 +1,79 @@
+package blockchain
+
+import (
+	"crypto/ecdsa"
+	crand "crypto/rand"
+	"crypto/sha256"
+	mrand "math/rand"
+)
+
+func newHash() Hash {
+	message := make([]byte, 256)
+	crand.Read(message)
+	return sha256.Sum256(message)
+}
+
+func newWallet() Wallet {
+	priv, _ := ecdsa.GenerateKey(curve, crand.Reader)
+	return (*wallet)(priv)
+}
+
+func newTxHashPointer() TxHashPointer {
+	return TxHashPointer{
+		BlockNumber: mrand.Uint32(),
+		Hash:        newHash(),
+	}
+}
+
+func newTxOutput() TxOutput {
+	return TxOutput{
+		Amount:    uint64(mrand.Int63()),
+		Recipient: newWallet().Public(),
+	}
+}
+
+func newTxBody() TxBody {
+	// Uniform distribution on [1, 4]
+	nOutputs := mrand.Intn(4) + 1
+	body := TxBody{
+		Sender:  newWallet().Public(),
+		Input:   newTxHashPointer(),
+		Outputs: make([]TxOutput, nOutputs),
+	}
+	for i := 0; i < nOutputs; i++ {
+		body.Outputs[i] = newTxOutput()
+	}
+	return body
+}
+
+func newTransaction() *Transaction {
+	sender := newWallet()
+	tbody := newTxBody()
+	digest := tbody.Hash()
+	sig := sender.Sign(digest, crand.Reader)
+	return &Transaction{
+		TxBody: tbody,
+		Sig:    sig,
+	}
+}
+
+func newBlockHeader() BlockHeader {
+	return BlockHeader{
+		BlockNumber: mrand.Uint32(),
+		LastBlock:   newHash(),
+		Miner:       newWallet().Public(),
+	}
+}
+
+func newBlock() *Block {
+	// Uniform distribution on [500, 999]
+	nTransactions := mrand.Intn(500) + 500
+	b := Block{
+		BlockHeader:  newBlockHeader(),
+		Transactions: make([]*Transaction, nTransactions),
+	}
+	for i := 0; i < nTransactions; i++ {
+		b.Transactions[i] = newTransaction()
+	}
+	return &b
+}