[#247] object: Introduce patcher package

* Introduce `patcher` package that contains such interfaces to be
  implemented:
  - `PatchApplier` - the main patching engine that merges the stream
    of patches and the stream of original object payload divided by
    ranges. The merged streams result is output to `ChunkedObjectWriter`;
  - `RangeProvider` - provides the original object payload by ranges;
  - `HeaderProvider` - provides the original object header.
* Introduce `patcher` that implements `PatchApplier`;
* Cover all possible cases with unit-tests.

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

object/patcher/patcher.go

@@ -0,0 +1,242 @@
+package patcher
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
+)
+
+var (
+	ErrOffsetExceedsSize       = errors.New("patch offset exceeds object size")
+	ErrInvalidPatchOffsetOrder = errors.New("invalid patch offset order")
+	ErrPayloadPatchIsNil       = errors.New("nil payload patch")
+	ErrAttrPatchAlreadyApplied = errors.New("attribute patch already applied")
+)
+
+// PatchRes is the result of patch application.
+type PatchRes struct {
+	AccessIdentifiers *transformer.AccessIdentifiers
+}
+
+// PatchApplier is the interface that provides method to apply header and payload patches.
+type PatchApplier interface {
+	// ApplyAttributesPatch applies the patch only for the object's attributes.
+	//
+	// ApplyAttributesPatch can't be invoked few times, otherwise it returns `ErrAttrPatchAlreadyApplied` error.
+	//
+	// The call is idempotent for the original header if it's invoked with empty `newAttrs` and
+	// `replaceAttrs = false`.
+	ApplyAttributesPatch(ctx context.Context, newAttrs []objectSDK.Attribute, replaceAttrs bool) error
+
+	// ApplyPayloadPatch applies the patch for the object's payload.
+	//
+	// ApplyPayloadPatch returns `ErrPayloadPatchIsNil` error if patch is nil.
+	ApplyPayloadPatch(ctx context.Context, payloadPatch *objectSDK.PayloadPatch) error
+
+	// Close closes PatchApplier when the patch stream is over.
+	Close(context.Context) (PatchRes, error)
+}
+
+// RangeProvider is the interface that provides a method to get original object payload
+// by a given range.
+type RangeProvider interface {
+	// GetRange reads an original object payload by the given range.
+	// The method returns io.Reader over the data range only. This means if the data is read out,
+	// then GetRange has to be invoked to provide reader over the next range.
+	GetRange(ctx context.Context, rng *objectSDK.Range) io.Reader
+}
+
+type patcher struct {
+	rangeProvider RangeProvider
+
+	objectWriter transformer.ChunkedObjectWriter
+
+	currOffset uint64
+
+	originalPayloadSize uint64
+
+	hdr *objectSDK.Object
+
+	attrPatchAlreadyApplied bool
+
+	readerBuffSize int
+}
+
+const (
+	DefaultReaderBufferSize = 64 * 1024
+)
+
+// Params is parameters to initialize patcher.
+type Params struct {
+	// Original object header.
+	Header *objectSDK.Object
+
+	// Range provider.
+	RangeProvider RangeProvider
+
+	// ObjectWriter is the writer that writes the patched object.
+	ObjectWriter transformer.ChunkedObjectWriter
+
+	// The size of the buffer used by the original payload range reader.
+	// If it's set to <=0, then `DefaultReaderBufferSize` is used.
+	ReaderBufferSize int
+}
+
+func New(prm Params) PatchApplier {
+	readerBufferSize := prm.ReaderBufferSize
+	if readerBufferSize <= 0 {
+		readerBufferSize = DefaultReaderBufferSize
+	}
+
+	return &patcher{
+		rangeProvider: prm.RangeProvider,
+
+		objectWriter: prm.ObjectWriter,
+
+		hdr: prm.Header,
+
+		originalPayloadSize: prm.Header.PayloadSize(),
+
+		readerBuffSize: readerBufferSize,
+	}
+}
+
+func (p *patcher) ApplyAttributesPatch(ctx context.Context, newAttrs []objectSDK.Attribute, replaceAttrs bool) error {
+	defer func() {
+		p.attrPatchAlreadyApplied = true
+	}()
+
+	if p.attrPatchAlreadyApplied {
+		return ErrAttrPatchAlreadyApplied
+	}
+
+	if replaceAttrs {
+		p.hdr.SetAttributes(newAttrs...)
+	} else if len(newAttrs) > 0 {
+		mergedAttrs := mergeAttributes(newAttrs, p.hdr.Attributes())
+		p.hdr.SetAttributes(mergedAttrs...)
+	}
+
+	if err := p.objectWriter.WriteHeader(ctx, p.hdr); err != nil {
+		return fmt.Errorf("writer header: %w", err)
+	}
+	return nil
+}
+
+func (p *patcher) ApplyPayloadPatch(ctx context.Context, payloadPatch *objectSDK.PayloadPatch) error {
+	if payloadPatch == nil {
+		return ErrPayloadPatchIsNil
+	}
+
+	if payloadPatch.Range.GetOffset() < p.currOffset {
+		return fmt.Errorf("%w: current = %d, previous = %d", ErrInvalidPatchOffsetOrder, payloadPatch.Range.GetOffset(), p.currOffset)
+	}
+
+	if payloadPatch.Range.GetOffset() > p.originalPayloadSize {
+		return fmt.Errorf("%w: offset = %d, object size = %d", ErrOffsetExceedsSize, payloadPatch.Range.GetOffset(), p.originalPayloadSize)
+	}
+
+	var err error
+	if p.currOffset, err = p.applyPatch(ctx, payloadPatch, p.currOffset); err != nil {
+		return fmt.Errorf("apply patch: %w", err)
+	}
+
+	return nil
+}
+
+func (p *patcher) Close(ctx context.Context) (PatchRes, error) {
+	rng := new(objectSDK.Range)
+	rng.SetOffset(p.currOffset)
+	rng.SetLength(p.originalPayloadSize - p.currOffset)
+
+	// copy remaining originial payload
+	if err := p.copyRange(ctx, rng); err != nil {
+		return PatchRes{}, fmt.Errorf("copy payload: %w", err)
+	}
+
+	aid, err := p.objectWriter.Close(ctx)
+	if err != nil {
+		return PatchRes{}, fmt.Errorf("close object writer: %w", err)
+	}
+
+	return PatchRes{
+		AccessIdentifiers: aid,
+	}, nil
+}
+
+func (p *patcher) copyRange(ctx context.Context, rng *objectSDK.Range) error {
+	rdr := p.rangeProvider.GetRange(ctx, rng)
+	for {
+		buffOrigPayload := make([]byte, p.readerBuffSize)
+		n, readErr := rdr.Read(buffOrigPayload)
+		if readErr != nil {
+			if readErr != io.EOF {
+				return fmt.Errorf("read: %w", readErr)
+			}
+		}
+		_, wrErr := p.objectWriter.Write(ctx, buffOrigPayload[:n])
+		if wrErr != nil {
+			return fmt.Errorf("write: %w", wrErr)
+		}
+		if readErr == io.EOF {
+			break
+		}
+	}
+	return nil
+}
+
+func (p *patcher) applyPatch(ctx context.Context, payloadPatch *objectSDK.PayloadPatch, offset uint64) (newOffset uint64, err error) {
+	// write the original payload chunk before the start of the patch
+	if payloadPatch.Range.GetOffset() > offset {
+		rng := new(objectSDK.Range)
+		rng.SetOffset(offset)
+		rng.SetLength(payloadPatch.Range.GetOffset() - offset)
+
+		if err = p.copyRange(ctx, rng); err != nil {
+			err = fmt.Errorf("copy payload: %w", err)
+			return
+		}
+
+		newOffset = payloadPatch.Range.GetOffset()
+	}
+
+	// apply patch
+	if _, err = p.objectWriter.Write(ctx, payloadPatch.Chunk); err != nil {
+		return
+	}
+
+	if payloadPatch.Range.GetLength() > 0 {
+		newOffset += payloadPatch.Range.GetLength()
+	}
+
+	return
+}
+
+func mergeAttributes(newAttrs, oldAttrs []objectSDK.Attribute) []objectSDK.Attribute {
+	attrMap := make(map[string]string, len(newAttrs))
+
+	for _, attr := range newAttrs {
+		attrMap[attr.Key()] = attr.Value()
+	}
+
+	for _, oldAttr := range oldAttrs {
+		newVal, ok := attrMap[oldAttr.Key()]
+		if !ok {
+			continue
+		}
+		oldAttr.SetValue(newVal)
+		delete(attrMap, oldAttr.Key())
+	}
+
+	for _, newAttr := range newAttrs {
+		if _, ok := attrMap[newAttr.Key()]; ok {
+			oldAttrs = append(oldAttrs, newAttr)
+		}
+	}
+
+	return oldAttrs
+}

object/patcher/patcher_test.go

@@ -0,0 +1,564 @@
+package patcher
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"testing"
+
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
+	"github.com/stretchr/testify/require"
+)
+
+type mockPatchedObjectWriter struct {
+	obj *objectSDK.Object
+}
+
+func (m *mockPatchedObjectWriter) Write(_ context.Context, chunk []byte) (int, error) {
+	res := append(m.obj.Payload(), chunk...)
+
+	m.obj.SetPayload(res)
+	m.obj.SetPayloadSize(uint64(len(res)))
+
+	return len(chunk), nil
+}
+
+func (m *mockPatchedObjectWriter) WriteHeader(_ context.Context, hdr *objectSDK.Object) error {
+	m.obj.ToV2().SetHeader(hdr.ToV2().GetHeader())
+	return nil
+}
+
+func (m *mockPatchedObjectWriter) Close(context.Context) (*transformer.AccessIdentifiers, error) {
+	return &transformer.AccessIdentifiers{}, nil
+}
+
+type mockRangeProvider struct {
+	originalObjectPayload []byte
+}
+
+var _ RangeProvider = (*mockRangeProvider)(nil)
+
+func (m *mockRangeProvider) GetRange(_ context.Context, rng *objectSDK.Range) io.Reader {
+	offset := rng.GetOffset()
+	length := rng.GetLength()
+
+	if length == 0 {
+		return bytes.NewReader(m.originalObjectPayload[offset:])
+	}
+	return bytes.NewReader(m.originalObjectPayload[offset : offset+length])
+}
+
+func newTestObject() (*objectSDK.Object, oid.Address) {
+	obj := objectSDK.New()
+
+	addr := oidtest.Address()
+	obj.SetContainerID(addr.Container())
+	obj.SetID(addr.Object())
+
+	return obj, addr
+}
+
+func rangeWithOffestWithLength(offset, length uint64) *objectSDK.Range {
+	rng := new(objectSDK.Range)
+	rng.SetOffset(offset)
+	rng.SetLength(length)
+	return rng
+}
+
+func TestPatchRevert(t *testing.T) {
+	obj, _ := newTestObject()
+
+	modifPatch := &objectSDK.Patch{
+		PayloadPatch: &objectSDK.PayloadPatch{
+			Range: rangeWithOffestWithLength(0, 0),
+
+			Chunk: []byte("inserted"),
+		},
+	}
+
+	originalObjectPayload := []byte("*******************")
+
+	obj.SetPayload(originalObjectPayload)
+	obj.SetPayloadSize(uint64(len(originalObjectPayload)))
+
+	exp := []byte("inserted*******************")
+
+	rangeProvider := &mockRangeProvider{
+		originalObjectPayload: originalObjectPayload,
+	}
+
+	patchedObj, _ := newTestObject()
+
+	wr := &mockPatchedObjectWriter{
+		obj: patchedObj,
+	}
+
+	prm := Params{
+		Header: obj.CutPayload(),
+
+		RangeProvider: rangeProvider,
+
+		ObjectWriter: wr,
+	}
+
+	patcher := New(prm)
+
+	err := patcher.ApplyAttributesPatch(context.Background(), modifPatch.NewAttributes, modifPatch.ReplaceAttributes)
+	require.NoError(t, err)
+
+	err = patcher.ApplyPayloadPatch(context.Background(), modifPatch.PayloadPatch)
+	require.NoError(t, err)
+
+	_, err = patcher.Close(context.Background())
+	require.NoError(t, err)
+
+	require.Equal(t, exp, patchedObj.Payload())
+
+	revertPatch := &objectSDK.Patch{
+		PayloadPatch: &objectSDK.PayloadPatch{
+			Range: rangeWithOffestWithLength(0, uint64(len("inserted"))),
+
+			Chunk: []byte{},
+		},
+	}
+
+	rangeProvider = &mockRangeProvider{
+		originalObjectPayload: exp,
+	}
+
+	patchedPatchedObj, _ := newTestObject()
+
+	wr = &mockPatchedObjectWriter{
+		obj: patchedPatchedObj,
+	}
+
+	prm = Params{
+		Header: patchedObj.CutPayload(),
+
+		RangeProvider: rangeProvider,
+
+		ObjectWriter: wr,
+	}
+
+	patcher = New(prm)
+
+	err = patcher.ApplyAttributesPatch(context.Background(), revertPatch.NewAttributes, revertPatch.ReplaceAttributes)
+	require.NoError(t, err)
+
+	err = patcher.ApplyPayloadPatch(context.Background(), revertPatch.PayloadPatch)
+	require.NoError(t, err)
+
+	_, err = patcher.Close(context.Background())
+	require.NoError(t, err)
+
+	require.Equal(t, originalObjectPayload, patchedPatchedObj.Payload())
+}
+
+func TestPatchRepeatAttributePatch(t *testing.T) {
+	obj, _ := newTestObject()
+
+	modifPatch := &objectSDK.Patch{}
+
+	originalObjectPayload := []byte("*******************")
+
+	obj.SetPayload(originalObjectPayload)
+	obj.SetPayloadSize(uint64(len(originalObjectPayload)))
+
+	rangeProvider := &mockRangeProvider{
+		originalObjectPayload: originalObjectPayload,
+	}
+
+	patchedObj, _ := newTestObject()
+
+	wr := &mockPatchedObjectWriter{
+		obj: patchedObj,
+	}
+
+	prm := Params{
+		Header: obj.CutPayload(),
+
+		RangeProvider: rangeProvider,
+
+		ObjectWriter: wr,
+	}
+
+	patcher := New(prm)
+
+	err := patcher.ApplyAttributesPatch(context.Background(), modifPatch.NewAttributes, modifPatch.ReplaceAttributes)
+	require.NoError(t, err)
+
+	err = patcher.ApplyAttributesPatch(context.Background(), modifPatch.NewAttributes, modifPatch.ReplaceAttributes)
+	require.ErrorIs(t, err, ErrAttrPatchAlreadyApplied)
+}
+
+func TestPatchEmptyPayloadPatch(t *testing.T) {
+	obj, _ := newTestObject()
+
+	modifPatch := &objectSDK.Patch{}
+
+	originalObjectPayload := []byte("*******************")
+
+	obj.SetPayload(originalObjectPayload)
+	obj.SetPayloadSize(uint64(len(originalObjectPayload)))
+
+	rangeProvider := &mockRangeProvider{
+		originalObjectPayload: originalObjectPayload,
+	}
+
+	patchedObj, _ := newTestObject()
+
+	wr := &mockPatchedObjectWriter{
+		obj: patchedObj,
+	}
+
+	prm := Params{
+		Header: obj.CutPayload(),
+
+		RangeProvider: rangeProvider,
+
+		ObjectWriter: wr,
+	}
+
+	patcher := New(prm)
+
+	err := patcher.ApplyAttributesPatch(context.Background(), modifPatch.NewAttributes, modifPatch.ReplaceAttributes)
+	require.NoError(t, err)
+
+	err = patcher.ApplyPayloadPatch(context.Background(), nil)
+	require.ErrorIs(t, err, ErrPayloadPatchIsNil)
+}
+
+func newTestAttribute(key, val string) objectSDK.Attribute {
+	var attr objectSDK.Attribute
+	attr.SetKey(key)
+	attr.SetValue(val)
+	return attr
+}
+
+func TestPatch(t *testing.T) {
+	for _, test := range []struct {
+		name                    string
+		patches                 []objectSDK.Patch
+		originalObjectPayload   []byte
+		patched                 []byte
+		expectedPayloadPatchErr error
+	}{
+		{
+			name: "invalid offset",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(100, 0),
+						Chunk: []byte(""),
+					},
+				},
+			},
+			originalObjectPayload:   []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			expectedPayloadPatchErr: ErrOffsetExceedsSize,
+		},
+		{
+			name: "invalid following patch offset",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(10, 0),
+						Chunk: []byte(""),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(7, 0),
+						Chunk: []byte(""),
+					},
+				},
+			},
+			originalObjectPayload:   []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			expectedPayloadPatchErr: ErrInvalidPatchOffsetOrder,
+		},
+		{
+			name: "only header patch",
+			patches: []objectSDK.Patch{
+				{
+					NewAttributes: []objectSDK.Attribute{
+						newTestAttribute("key1", "val2"),
+						newTestAttribute("key2", "val2"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "header and payload",
+			patches: []objectSDK.Patch{
+				{
+					NewAttributes: []objectSDK.Attribute{
+						newTestAttribute("key1", "val2"),
+						newTestAttribute("key2", "val2"),
+					},
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 0),
+						Chunk: []byte("inserted at the beginning"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("inserted at the beginning0123456789qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "header only then payload",
+			patches: []objectSDK.Patch{
+				{
+					NewAttributes: []objectSDK.Attribute{
+						newTestAttribute("key1", "val2"),
+						newTestAttribute("key2", "val2"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 0),
+						Chunk: []byte("inserted at the beginning"),
+					},
+				},
+			},
+			originalObjectPayload:   []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:                 []byte("inserted at the beginning0123456789qwertyuiopasdfghjklzxcvbnm"),
+			expectedPayloadPatchErr: ErrPayloadPatchIsNil,
+		},
+		{
+			name: "no effect",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 0),
+						Chunk: []byte(""),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(12, 0),
+						Chunk: []byte(""),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(20, 0),
+						Chunk: []byte(""),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "insert prefix",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 0),
+						Chunk: []byte("inserted at the beginning"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("inserted at the beginning0123456789qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "insert in the middle",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(5, 0),
+						Chunk: []byte("inserted somewhere in the middle"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("01234inserted somewhere in the middle56789qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "insert at the end",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(36, 0),
+						Chunk: []byte("inserted somewhere at the end"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("0123456789qwertyuiopasdfghjklzxcvbnminserted somewhere at the end"),
+		},
+		{
+			name: "replace by range",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 12),
+						Chunk: []byte("just replace"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("just replaceertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "replace and insert some bytes",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 11),
+						Chunk: []byte("replace and append in the middle"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("replace and append in the middlewertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "replace and insert some bytes in the middle",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(5, 3),
+						Chunk: []byte("@@@@@"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("01234@@@@@89qwertyuiopasdfghjklzxcvbnm"),
+		},
+		{
+			name: "a few patches: prefix, suffix",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(0, 0),
+						Chunk: []byte("this_will_be_prefix"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(36, 0),
+						Chunk: []byte("this_will_be_suffix"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patched:               []byte("this_will_be_prefix0123456789qwertyuiopasdfghjklzxcvbnmthis_will_be_suffix"),
+		},
+		{
+			name: "a few patches: replace and insert some bytes",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(10, 3),
+						Chunk: []byte("aaaaa"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(16, 0),
+						Chunk: []byte("bbbbb"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("0123456789ABCDEF"),
+			patched:               []byte("0123456789aaaaaDEFbbbbb"),
+		},
+		{
+			name: "a few patches: various modifiactions",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(4, 8),
+						Chunk: []byte("earliest"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(13, 0),
+						Chunk: []byte("known "),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(35, 8),
+						Chunk: []byte("a small town"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(62, 6),
+						Chunk: []byte("tablet"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(87, 0),
+						Chunk: []byte("Shar-Kali-Sharri"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("The ******** mention of Babylon as [insert] appears on a clay ****** from the reign of "),
+			patched:               []byte("The earliest known mention of Babylon as a small town appears on a clay tablet from the reign of Shar-Kali-Sharri"),
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			rangeProvider := &mockRangeProvider{
+				originalObjectPayload: test.originalObjectPayload,
+			}
+
+			originalObject, _ := newTestObject()
+			originalObject.SetPayload(test.originalObjectPayload)
+			originalObject.SetPayloadSize(uint64(len(test.originalObjectPayload)))
+
+			patchedObject, _ := newTestObject()
+
+			wr := &mockPatchedObjectWriter{
+				obj: patchedObject,
+			}
+
+			prm := Params{
+				Header: originalObject.CutPayload(),
+
+				RangeProvider: rangeProvider,
+
+				ObjectWriter: wr,
+			}
+
+			patcher := New(prm)
+
+			for i, patch := range test.patches {
+				if i == 0 {
+					_ = patcher.ApplyAttributesPatch(context.Background(), patch.NewAttributes, patch.ReplaceAttributes)
+				}
+
+				if patch.PayloadPatch == nil {
+					continue
+				}
+
+				err := patcher.ApplyPayloadPatch(context.Background(), patch.PayloadPatch)
+				if err != nil {
+					if test.expectedPayloadPatchErr != nil {
+						require.ErrorIs(t, err, test.expectedPayloadPatchErr)
+						return
+					} else {
+						require.NoError(t, err)
+					}
+				}
+			}
+
+			_, err := patcher.Close(context.Background())
+			require.NoError(t, err)
+			require.Equal(t, test.patched, patchedObject.Payload())
+
+			newAttrs := append([]objectSDK.Attribute{}, test.patches[0].NewAttributes...)
+			require.Equal(t, newAttrs, patchedObject.Attributes())
+		})
+	}
+
+}