1 files changed, 226 insertions, 0 deletions
diff --git a/pack_write_test.go b/pack_write_test.go
new file mode 100644
index 00000000..d33ae012
--- /dev/null
+++ b/pack_write_test.go
@@ -0,0 +1,226 @@
+package furgit
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestPackHeaderEncodeParseRoundtrip(t *testing.T) {
+	cases := []struct {
+		ty    ObjectType
+		sizes []int
+	}{
+		{ObjectTypeCommit, []int{0, 1, 15, 16, 127, 128, 1024, 1 << 20}},
+		{ObjectTypeTree, []int{0, 3, 31, 32, 255, 256, 4096}},
+		{ObjectTypeBlob, []int{0, 7, 63, 64, 511, 512, 99999}},
+		{ObjectTypeTag, []int{0, 2, 14, 15, 16, 127, 128}},
+	}
+
+	for _, c := range cases {
+		for _, size := range c.sizes {
+			encoded, err := packHeaderEncode(c.ty, size)
+			if err != nil {
+				t.Fatalf("packHeaderEncode(%v,%d) error: %v", c.ty, size, err)
+			}
+			gotTy, gotSize, consumed, err := packHeaderParse(encoded)
+			if err != nil {
+				t.Fatalf("packHeaderParse error: %v", err)
+			}
+			if gotTy != c.ty || gotSize != size {
+				t.Fatalf("roundtrip mismatch: got (%v,%d), want (%v,%d)", gotTy, gotSize, c.ty, size)
+			}
+			if consumed != len(encoded) {
+				t.Fatalf("consumed=%d, encoded=%d", consumed, len(encoded))
+			}
+		}
+	}
+}
+
+func TestPackVarintEncodeRoundtrip(t *testing.T) {
+	values := []int{0, 1, 2, 7, 8, 127, 128, 129, 255, 1024, 1 << 20}
+	for _, v := range values {
+		encoded, err := packVarintEncode(v)
+		if err != nil {
+			t.Fatalf("packVarintEncode(%d) error: %v", v, err)
+		}
+		pos := 0
+		got, err := packVarintRead(encoded, &pos)
+		if err != nil {
+			t.Fatalf("packVarintRead error: %v", err)
+		}
+		if got != v {
+			t.Fatalf("roundtrip mismatch: got %d, want %d", got, v)
+		}
+		if pos != len(encoded) {
+			t.Fatalf("pos=%d, encoded=%d", pos, len(encoded))
+		}
+	}
+}
+
+func TestPackOfsEncodeRoundtrip(t *testing.T) {
+	values := []uint64{1, 2, 7, 8, 9, 0x7f, 0x80, 0x81, 0x1000, 0x12345}
+	for _, v := range values {
+		encoded, err := packOfsEncode(v)
+		if err != nil {
+			t.Fatalf("packOfsEncode(%d) error: %v", v, err)
+		}
+		dist, consumed, err := packDeltaReadOfsDistance(encoded)
+		if err != nil {
+			t.Fatalf("packDeltaReadOfsDistance error: %v", err)
+		}
+		if dist != v {
+			t.Fatalf("roundtrip mismatch: got %d, want %d", dist, v)
+		}
+		if consumed != len(encoded) {
+			t.Fatalf("consumed=%d, encoded=%d", consumed, len(encoded))
+		}
+	}
+}
+
+func TestPackWriteNoDeltas(t *testing.T) {
+	repoPath, cleanup := setupTestRepo(t)
+	defer cleanup()
+
+	workDir, cleanupWork := setupWorkDir(t)
+	defer cleanupWork()
+
+	if err := os.WriteFile(filepath.Join(workDir, "file1.txt"), []byte("content1"), 0o644); err != nil {
+		t.Fatalf("failed to write file1.txt: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(workDir, "file2.txt"), []byte("content2"), 0o644); err != nil {
+		t.Fatalf("failed to write file2.txt: %v", err)
+	}
+
+	gitCmd(t, repoPath, "--work-tree="+workDir, "add", ".")
+	gitCmd(t, repoPath, "--work-tree="+workDir, "commit", "-m", "Test commit")
+	commitHash := gitCmd(t, repoPath, "rev-parse", "HEAD")
+
+	commitBody := gitCatFile(t, repoPath, "commit", commitHash)
+	lines := bytes.Split(commitBody, []byte{'\n'})
+	if len(lines) == 0 || !bytes.HasPrefix(lines[0], []byte("tree ")) {
+		t.Fatalf("commit missing tree header")
+	}
+	treeHash := strings.TrimSpace(string(bytes.TrimPrefix(lines[0], []byte("tree "))))
+
+	lsTree := gitCmd(t, repoPath, "ls-tree", "-r", treeHash)
+	var blobHashes []string
+	for _, line := range strings.Split(lsTree, "\n") {
+		if line == "" {
+			continue
+		}
+		fields := strings.Fields(line)
+		if len(fields) < 3 {
+			t.Fatalf("unexpected ls-tree line: %q", line)
+		}
+		blobHashes = append(blobHashes, fields[2])
+	}
+
+	repo, err := OpenRepository(repoPath)
+	if err != nil {
+		t.Fatalf("OpenRepository failed: %v", err)
+	}
+	defer func() { _ = repo.Close() }()
+
+	var objects []Hash
+	commitID, _ := repo.ParseHash(commitHash)
+	objects = append(objects, commitID)
+	treeID, _ := repo.ParseHash(treeHash)
+	objects = append(objects, treeID)
+	for _, bh := range blobHashes {
+		id, _ := repo.ParseHash(bh)
+		objects = append(objects, id)
+	}
+	expectedOids := append([]string{commitHash, treeHash}, blobHashes...)
+
+	packDir := filepath.Join(repoPath, "objects", "pack")
+	if err := os.MkdirAll(packDir, 0o755); err != nil {
+		t.Fatalf("failed to create pack dir: %v", err)
+	}
+	pf, err := os.CreateTemp(packDir, "furgit-test-*.pack")
+	if err != nil {
+		t.Fatalf("failed to create pack file: %v", err)
+	}
+	packPath := pf.Name()
+	idxPath := strings.TrimSuffix(packPath, ".pack") + ".idx"
+	if _, err := repo.packWrite(pf, objects, packWriteOptions{}); err != nil {
+		_ = pf.Close()
+		t.Fatalf("packWrite failed: %v", err)
+	}
+	if err := pf.Close(); err != nil {
+		t.Fatalf("failed to close pack file: %v", err)
+	}
+
+	defer func() {
+		_ = os.Remove(packPath)
+		_ = os.Remove(idxPath)
+	}()
+
+	_ = gitCmd(t, repoPath, "index-pack", "-o", idxPath, packPath)
+
+	verifyOut := gitCmd(t, repoPath, "verify-pack", "-v", idxPath)
+	seen := make(map[string]struct{})
+	for _, line := range strings.Split(verifyOut, "\n") {
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+		if strings.HasPrefix(line, "chain length") || strings.HasPrefix(line, "non delta") {
+			continue
+		}
+		parts := strings.Fields(line)
+		if len(parts) == 0 {
+			continue
+		}
+		seen[parts[0]] = struct{}{}
+	}
+	for _, oid := range expectedOids {
+		if _, ok := seen[oid]; !ok {
+			t.Fatalf("verify-pack missing object %s", oid)
+		}
+	}
+
+	for _, oid := range expectedOids {
+		if err := removeLooseObject(repoPath, oid); err != nil {
+			t.Fatalf("remove loose object %s: %v", oid, err)
+		}
+	}
+	for _, oid := range expectedOids {
+		_ = gitCmd(t, repoPath, "cat-file", "-p", oid)
+	}
+
+	_ = gitCmd(t, repoPath, "fsck", "--full", "--strict")
+}
+
+func TestPackWriteDeltasUnimplemented(t *testing.T) {
+	repoPath, cleanup := setupTestRepo(t)
+	defer cleanup()
+
+	repo, err := OpenRepository(repoPath)
+	if err != nil {
+		t.Fatalf("OpenRepository failed: %v", err)
+	}
+	defer func() { _ = repo.Close() }()
+
+	buf := new(bytes.Buffer)
+	_, err = repo.packWrite(buf, nil, packWriteOptions{EnableDeltas: true})
+	if !errors.Is(err, errPackDeltaUnimplemented) {
+		t.Fatalf("expected errPackDeltaUnimplemented, got %v", err)
+	}
+}
+
+func removeLooseObject(repoPath, oid string) error {
+	if len(oid) < 2 {
+		return ErrInvalidObject
+	}
+	path := filepath.Join(repoPath, "objects", oid[:2], oid[2:])
+	if err := os.Remove(path); err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	return nil
+}