Prepare for upstream PR

diff_test.go

@@ -39,6 +39,29 @@ func TestDiffRoundTrip(t *testing.T) {
 	require.Equal(t, changeSets, extractChangeSets)
 }
 
+func TestLegacyDiffRoundTrip(t *testing.T) {
+	changeSets := genChangeSets(rand.New(rand.NewSource(0)), 300)
+
+	// apply changeSets to tree
+	db := dbm.NewMemDB()
+	tree := NewLegacyMutableTree(db, 0, true, false, nil, log.NewNopLogger())
+	for i := range changeSets {
+		v, err := tree.SaveChangeSet(changeSets[i])
+		require.NoError(t, err)
+		require.Equal(t, int64(i+1), v)
+	}
+
+	// extract change sets from db
+	var extractChangeSets []*ChangeSet
+	tree2 := NewLegacyMutableTree(db, 0, true, false, nil, log.NewNopLogger())
+	err := tree2.TraverseStateChanges(0, math.MaxInt64, func(_ int64, changeSet *ChangeSet) error {
+		extractChangeSets = append(extractChangeSets, changeSet)
+		return nil
+	})
+	require.NoError(t, err)
+	require.Equal(t, changeSets, extractChangeSets)
+}
+
 func genChangeSets(r *rand.Rand, n int) []*ChangeSet {
 	var changeSets []*ChangeSet