Add new sorting method for blocks

- Add types.ByHeight to sort slice of blocks by their heights.
- Add test case for sorting methods of types.Block.

2 files changed, 65 insertions, 0 deletions

diff --git a/core/types/block.go b/core/types/block.go
index 217ea73..61b6535 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -87,3 +87,18 @@ func (b ByHash) Less(i int, j int) bool {
 func (b ByHash) Swap(i int, j int) {
 	b[i], b[j] = b[j], b[i]
 }
+
+// ByHeight is the helper type for sorting slice of blocks by height.
+type ByHeight []*Block
+
+func (b ByHeight) Len() int {
+	return len(b)
+}
+
+func (b ByHeight) Less(i int, j int) bool {
+	return b[i].Height < b[j].Height
+}
+
+func (b ByHeight) Swap(i int, j int) {
+	b[i], b[j] = b[j], b[i]
+}
diff --git a/core/types/block_test.go b/core/types/block_test.go
new file mode 100644
index 0000000..feca5b8
--- /dev/null
+++ b/core/types/block_test.go
@@ -0,0 +1,50 @@
+package types
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/stretchr/testify/suite"
+)
+
+type BlockTestSuite struct {
+	suite.Suite
+}
+
+func (s *BlockTestSuite) TestSortByHash() {
+	hash := common.Hash{}
+	copy(hash[:], "aaaaaa")
+	b0 := &Block{Hash: hash}
+	copy(hash[:], "bbbbbb")
+	b1 := &Block{Hash: hash}
+	copy(hash[:], "cccccc")
+	b2 := &Block{Hash: hash}
+	copy(hash[:], "dddddd")
+	b3 := &Block{Hash: hash}
+
+	blocks := []*Block{b3, b2, b1, b0}
+	sort.Sort(ByHash(blocks))
+	s.Equal(blocks[0].Hash, b0.Hash)
+	s.Equal(blocks[1].Hash, b1.Hash)
+	s.Equal(blocks[2].Hash, b2.Hash)
+	s.Equal(blocks[3].Hash, b3.Hash)
+}
+
+func (s *BlockTestSuite) TestSortByHeight() {
+	b0 := &Block{Height: 0}
+	b1 := &Block{Height: 1}
+	b2 := &Block{Height: 2}
+	b3 := &Block{Height: 3}
+
+	blocks := []*Block{b3, b2, b1, b0}
+	sort.Sort(ByHeight(blocks))
+	s.Equal(blocks[0].Hash, b0.Hash)
+	s.Equal(blocks[1].Hash, b1.Hash)
+	s.Equal(blocks[2].Hash, b2.Hash)
+	s.Equal(blocks[3].Hash, b3.Hash)
+}
+
+func TestBlock(t *testing.T) {
+	suite.Run(t, new(BlockTestSuite))
+}