bug(merkle-tree): fix out of index error in even nodes case

merkle_tree.go

@@ -38,6 +38,10 @@ func NewMerkleTree(data [][]byte) *MerkleTree {
 		}
 
 		nodes = newLevel
+
+		if len(newLevel) == 1 {
+			break
+		}
 	}
 
 	mTree := MerkleTree{&nodes[0]}

merkle_tree_test.go

@@ -49,7 +49,7 @@ func TestNewMerkleNode(t *testing.T) {
 	)
 }
 
-func TestNewMerkleTree(t *testing.T) {
+func TestNewMerkleTreeOddNodes(t *testing.T) {
 	data := [][]byte{
 		[]byte("node1"),
 		[]byte("node2"),
@@ -73,3 +73,45 @@ func TestNewMerkleTree(t *testing.T) {
 
 	assert.Equal(t, rootHash, fmt.Sprintf("%x", mTree.RootNode.Data), "Merkle tree root hash is correct")
 }
+
+func TestNewMerkleTreeEvenNodes(t *testing.T) {
+
+	data := [][]byte{
+		[]byte("node1"),
+		[]byte("node2"),
+		[]byte("node3"),
+		[]byte("node4"),
+		[]byte("node5"),
+		[]byte("node6"),
+		[]byte("node7"),
+		[]byte("node8"),
+	}
+
+	// Level 1
+	n1 := NewMerkleNode(nil, nil, data[0])
+	n2 := NewMerkleNode(nil, nil, data[1])
+	n3 := NewMerkleNode(nil, nil, data[2])
+	n4 := NewMerkleNode(nil, nil, data[3])
+	n5 := NewMerkleNode(nil, nil, data[4])
+	n6 := NewMerkleNode(nil, nil, data[5])
+	n7 := NewMerkleNode(nil, nil, data[6])
+	n8 := NewMerkleNode(nil, nil, data[7])
+
+	// Level 2
+	n9 := NewMerkleNode(n1, n2, nil)
+	n10 := NewMerkleNode(n3, n4, nil)
+	n11 := NewMerkleNode(n5, n6, nil)
+	n12 := NewMerkleNode(n7, n8, nil)
+
+	// Level 3
+	n13 := NewMerkleNode(n9, n10, nil)
+	n14 := NewMerkleNode(n11, n12, nil)
+
+	// Level 4
+	n15 := NewMerkleNode(n13, n14, nil)
+
+	rootHash := fmt.Sprintf("%x", n15.Data)
+	mTree := NewMerkleTree(data)
+
+	assert.Equal(t, rootHash, fmt.Sprintf("%x", mTree.RootNode.Data), "Merkle tree root hash is correct")
+}