[#242] object: Require only 1 field to be set for SplitInfo

Also write more tests.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

object/splitinfo.go

@@ -110,31 +110,30 @@ func (s *SplitInfo) UnmarshalJSON(data []byte) error {
 	return formatCheckSI((*object.SplitInfo)(s))
 }
 
-var errLinkNotSet = errors.New("link object ID is not set")
+var errSplitInfoMissingFields = errors.New("neither link object ID nor last part object ID is set")
-var errLastPartNotSet = errors.New("last part object ID is not set")
 
 func formatCheckSI(v2 *object.SplitInfo) error {
-	var oID oid.ID
-
 	link := v2.GetLink()
-	if link == nil {
+	lastPart := v2.GetLastPart()
-		return errLinkNotSet
+	if link == nil && lastPart == nil {
+		return errSplitInfoMissingFields
 	}
 
+	var oID oid.ID
+
+	if link != nil {
 		err := oID.ReadFromV2(*link)
 		if err != nil {
 			return fmt.Errorf("could not convert link object ID: %w", err)
 		}
-
-	lastPart := v2.GetLastPart()
-	if lastPart == nil {
-		return errLastPartNotSet
 	}
 
-	err = oID.ReadFromV2(*lastPart)
+	if lastPart != nil {
+		err := oID.ReadFromV2(*lastPart)
 		if err != nil {
 			return fmt.Errorf("could not convert last part object ID: %w", err)
 		}
+	}
 
 	return nil
 }

object/splitinfo_test.go

@@ -29,15 +29,16 @@ func TestSplitInfo(t *testing.T) {
 	l, set := s.Link()
 	require.True(t, set)
 	require.Equal(t, link, l)
+}
 
-	t.Run("to and from v2", func(t *testing.T) {
+func TestSplitInfoMarshal(t *testing.T) {
+	testToV2 := func(t *testing.T, s *object.SplitInfo) {
 		v2 := s.ToV2()
 		newS := object.NewSplitInfoFromV2(v2)
 
 		require.Equal(t, s, newS)
-	})
+	}
-
+	testMarshal := func(t *testing.T, s *object.SplitInfo) {
-	t.Run("marshal and unmarshal", func(t *testing.T) {
 		data, err := s.Marshal()
 		require.NoError(t, err)
 
@@ -46,6 +47,40 @@ func TestSplitInfo(t *testing.T) {
 		err = newS.Unmarshal(data)
 		require.NoError(t, err)
 		require.Equal(t, s, newS)
+	}
+
+	t.Run("good, both fields are set", func(t *testing.T) {
+		s := object.NewSplitInfo()
+		s.SetSplitID(object.NewSplitID())
+		s.SetLink(generateID())
+		s.SetLastPart(generateID())
+
+		testToV2(t, s)
+		testMarshal(t, s)
+	})
+	t.Run("good, only link is set", func(t *testing.T) {
+		s := object.NewSplitInfo()
+		s.SetSplitID(object.NewSplitID())
+		s.SetLink(generateID())
+
+		testToV2(t, s)
+		testMarshal(t, s)
+	})
+	t.Run("good, only last part is set", func(t *testing.T) {
+		s := object.NewSplitInfo()
+		s.SetSplitID(object.NewSplitID())
+		s.SetLastPart(generateID())
+
+		testToV2(t, s)
+		testMarshal(t, s)
+	})
+	t.Run("bad, no fields are set", func(t *testing.T) {
+		s := object.NewSplitInfo()
+		s.SetSplitID(object.NewSplitID())
+
+		data, err := s.Marshal()
+		require.NoError(t, err)
+		require.Error(t, object.NewSplitInfo().Unmarshal(data))
 	})
 }
 
@@ -96,6 +131,7 @@ func TestNewSplitInfo(t *testing.T) {
 }
 
 func TestSplitInfoMarshalJSON(t *testing.T) {
+	t.Run("good", func(t *testing.T) {
 		s := object.NewSplitInfo()
 		s.SetSplitID(object.NewSplitID())
 		s.SetLastPart(generateID())
@@ -107,4 +143,13 @@ func TestSplitInfoMarshalJSON(t *testing.T) {
 		actual := object.NewSplitInfo()
 		require.NoError(t, json.Unmarshal(data, actual))
 		require.Equal(t, s, actual)
+	})
+	t.Run("bad link", func(t *testing.T) {
+		data := `{"splitId":"Sn707289RrqDyJOrZMbMoQ==","lastPart":{"value":"Y7baWE0UdUOBr1ELKX3Q5v1LKRubQUbI81Q5UxCVeow="},"link":{"value":"bad"}}`
+		require.Error(t, json.Unmarshal([]byte(data), object.NewSplitInfo()))
+	})
+	t.Run("bad last part", func(t *testing.T) {
+		data := `{"splitId":"Sn707289RrqDyJOrZMbMoQ==","lastPart":{"value":"bad"},"link":{"value":"eRyPNCNNxHfxPcjijlv05HEcdoep/b7eHNLRSmDlnts="}}`
+		require.Error(t, json.Unmarshal([]byte(data), object.NewSplitInfo()))
+	})
 }