[DEV-226] Fix sorting of hashes in blockset.hashes() (#98)

* [DEV-226] Fix sorting of hashes in blockset.hashes()

* [DEV-226] add TestHashes

blockdag/blockset.go

@@ -130,7 +130,7 @@ func (bs blockSet) hashes() []daghash.Hash {
 		hashes = append(hashes, hash)
 	}
 	sort.Slice(hashes, func(i, j int) bool {
-		return daghash.Less(&hashes[j], &hashes[i])
+		return daghash.Less(&hashes[i], &hashes[j])
 	})
 	return hashes
 }

blockdag/blockset_test.go

@@ -0,0 +1,35 @@
+package blockdag
+
+import (
+	"testing"
+
+	"github.com/daglabs/btcd/dagconfig/daghash"
+)
+
+func TestHashes(t *testing.T) {
+	bs := setFromSlice(
+		&blockNode{
+			hash: daghash.Hash{3},
+		},
+		&blockNode{
+			hash: daghash.Hash{1},
+		},
+		&blockNode{
+			hash: daghash.Hash{0},
+		},
+		&blockNode{
+			hash: daghash.Hash{2},
+		},
+	)
+
+	expected := []daghash.Hash{
+		daghash.Hash{0},
+		daghash.Hash{1},
+		daghash.Hash{2},
+		daghash.Hash{3},
+	}
+
+	if !daghash.AreEqual(bs.hashes(), expected) {
+		t.Errorf("TestHashes: hashes are not ordered as expected")
+	}
+}