From 7f2a931fb6206cdfc47c5cceb857964ed6dff34c Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Thu, 13 Aug 2020 13:57:30 +0300
Subject: [PATCH] core: add tests for (*Blockchain).verifyHeader

---
 pkg/core/blockchain.go      | 13 ++++++++++---
 pkg/core/blockchain_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 386d24dab..14353cdff 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -1179,15 +1179,22 @@ func (bc *Blockchain) ApplyPolicyToTxSet(txes []*transaction.Transaction) []*tra
 	return txes
 }
 
+// Various errors that could be returns upon header verification.
+var (
+	ErrHdrHashMismatch     = errors.New("previous header hash doesn't match")
+	ErrHdrIndexMismatch    = errors.New("previous header index doesn't match")
+	ErrHdrInvalidTimestamp = errors.New("block is not newer than the previous one")
+)
+
 func (bc *Blockchain) verifyHeader(currHeader, prevHeader *block.Header) error {
 	if prevHeader.Hash() != currHeader.PrevHash {
-		return errors.New("previous header hash doesn't match")
+		return ErrHdrHashMismatch
 	}
 	if prevHeader.Index+1 != currHeader.Index {
-		return errors.New("previous header index doesn't match")
+		return ErrHdrIndexMismatch
 	}
 	if prevHeader.Timestamp >= currHeader.Timestamp {
-		return errors.New("block is not newer than the previous one")
+		return ErrHdrInvalidTimestamp
 	}
 	return bc.verifyHeaderWitnesses(currHeader, prevHeader)
 }
diff --git a/pkg/core/blockchain_test.go b/pkg/core/blockchain_test.go
index 655831d8c..eaebeb630 100644
--- a/pkg/core/blockchain_test.go
+++ b/pkg/core/blockchain_test.go
@@ -26,6 +26,33 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestVerifyHeader(t *testing.T) {
+	bc := newTestChain(t)
+	defer bc.Close()
+	prev := bc.topBlock.Load().(*block.Block).Header()
+	t.Run("Invalid", func(t *testing.T) {
+		t.Run("Hash", func(t *testing.T) {
+			h := prev.Hash()
+			h[0] = ^h[0]
+			hdr := newBlock(bc.config, 1, h).Header()
+			require.True(t, errors.Is(bc.verifyHeader(hdr, prev), ErrHdrHashMismatch))
+		})
+		t.Run("Index", func(t *testing.T) {
+			hdr := newBlock(bc.config, 3, prev.Hash()).Header()
+			require.True(t, errors.Is(bc.verifyHeader(hdr, prev), ErrHdrIndexMismatch))
+		})
+		t.Run("Timestamp", func(t *testing.T) {
+			hdr := newBlock(bc.config, 1, prev.Hash()).Header()
+			hdr.Timestamp = 0
+			require.True(t, errors.Is(bc.verifyHeader(hdr, prev), ErrHdrInvalidTimestamp))
+		})
+	})
+	t.Run("Valid", func(t *testing.T) {
+		hdr := newBlock(bc.config, 1, prev.Hash()).Header()
+		require.NoError(t, bc.verifyHeader(hdr, prev))
+	})
+}
+
 func TestAddHeaders(t *testing.T) {
 	bc := newTestChain(t)
 	defer bc.Close()