4 files changed, 44 insertions, 3 deletions
diff --git a/plumbing/format/index/index.go b/plumbing/format/index/index.go
index 649416a..f4c7647 100644
--- a/plumbing/format/index/index.go
+++ b/plumbing/format/index/index.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/go-git/go-git/v5/plumbing"
@@ -211,3 +212,20 @@ type EndOfIndexEntry struct {
 	//	their contents).
 	Hash plumbing.Hash
 }
+
+// SkipUnless applies patterns in the form of A, A/B, A/B/C
+// to the index to prevent the files from being checked out
+func (i *Index) SkipUnless(patterns []string) {
+	for _, e := range i.Entries {
+		var include bool
+		for _, pattern := range patterns {
+			if strings.HasPrefix(e.Name, pattern) {
+				include = true
+				break
+			}
+		}
+		if !include {
+			e.SkipWorktree = true
+		}
+	}
+}
diff --git a/plumbing/object/treenoder.go b/plumbing/object/treenoder.go
index b4891b9..6e7b334 100644
--- a/plumbing/object/treenoder.go
+++ b/plumbing/object/treenoder.go
@@ -38,6 +38,10 @@ func NewTreeRootNode(t *Tree) noder.Noder {
 	}
 }
 
+func (t *treeNoder) Skip() bool {
+	return false
+}
+
 func (t *treeNoder) isRoot() bool {
 	return t.name == ""
 }
diff --git a/plumbing/protocol/packp/updreq.go b/plumbing/protocol/packp/updreq.go
index 46ad6fd..5dbd8ac 100644
--- a/plumbing/protocol/packp/updreq.go
+++ b/plumbing/protocol/packp/updreq.go
@@ -87,9 +87,9 @@ type Action string
 
 const (
 	Create  Action = "create"
-	Update         = "update"
-	Delete         = "delete"
-	Invalid        = "invalid"
+	Update  Action = "update"
+	Delete  Action = "delete"
+	Invalid Action = "invalid"
 )
 
 type Command struct {
diff --git a/plumbing/protocol/packp/updreq_encode_test.go b/plumbing/protocol/packp/updreq_encode_test.go
index 6ba0043..4370b79 100644
--- a/plumbing/protocol/packp/updreq_encode_test.go
+++ b/plumbing/protocol/packp/updreq_encode_test.go
@@ -170,3 +170,22 @@ func (s *UpdReqEncodeSuite) TestPushOptions(c *C) {
 
 	s.testEncode(c, r, expected)
 }
+
+func (s *UpdReqEncodeSuite) TestPushAtomic(c *C) {
+	hash1 := plumbing.NewHash("1ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	hash2 := plumbing.NewHash("2ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	name := plumbing.ReferenceName("myref")
+
+	r := NewReferenceUpdateRequest()
+	r.Capabilities.Set(capability.Atomic)
+	r.Commands = []*Command{
+		{Name: name, Old: hash1, New: hash2},
+	}
+
+	expected := pktlines(c,
+		"1ecf0ef2c2dffb796033e5a02219af86ec6584e5 2ecf0ef2c2dffb796033e5a02219af86ec6584e5 myref\x00atomic",
+		pktline.FlushString,
+	)
+
+	s.testEncode(c, r, expected)
+}