refstore/packed: Add packed refs backend

1 files changed, 176 insertions, 0 deletions

diff --git a/refstore/packed/packed_test.go b/refstore/packed/packed_test.go
new file mode 100644
index 00000000..2c984cb9
--- /dev/null
+++ b/refstore/packed/packed_test.go
@@ -0,0 +1,176 @@
+package packed_test
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"path/filepath"
+	"slices"
+	"testing"
+
+	"codeberg.org/lindenii/furgit/internal/testgit"
+	"codeberg.org/lindenii/furgit/objectid"
+	"codeberg.org/lindenii/furgit/ref"
+	"codeberg.org/lindenii/furgit/refstore"
+	"codeberg.org/lindenii/furgit/refstore/packed"
+)
+
+func openPackedRefStoreFromRepo(t *testing.T, repoPath string, algo objectid.Algorithm) *packed.Store {
+	t.Helper()
+	file, err := os.Open(filepath.Join(repoPath, "packed-refs"))
+	if err != nil {
+		t.Fatalf("open packed-refs: %v", err)
+	}
+	defer func() { _ = file.Close() }()
+
+	store, err := packed.New(file, algo)
+	if err != nil {
+		t.Fatalf("packed.New: %v", err)
+	}
+	return store
+}
+
+func TestPackedResolveAndPeeled(t *testing.T) {
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) {
+		testRepo := testgit.NewBareRepo(t, algo)
+		_, _, commitID := testRepo.MakeCommit(t, "packed refs commit")
+		testRepo.UpdateRef(t, "refs/heads/main", commitID)
+		tagID := testRepo.TagAnnotated(t, "v1.0.0", commitID, "annotated tag")
+		testRepo.PackRefs(t, "--all", "--prune")
+
+		store := openPackedRefStoreFromRepo(t, testRepo.Dir(), algo)
+
+		resolvedMain, err := store.Resolve("refs/heads/main")
+		if err != nil {
+			t.Fatalf("Resolve(main): %v", err)
+		}
+		mainDet, ok := resolvedMain.(ref.Detached)
+		if !ok {
+			t.Fatalf("Resolve(main) type = %T, want ref.Detached", resolvedMain)
+		}
+		if mainDet.ID != commitID {
+			t.Fatalf("Resolve(main) id = %s, want %s", mainDet.ID, commitID)
+		}
+
+		resolvedTag, err := store.Resolve("refs/tags/v1.0.0")
+		if err != nil {
+			t.Fatalf("Resolve(tag): %v", err)
+		}
+		tagDet, ok := resolvedTag.(ref.Detached)
+		if !ok {
+			t.Fatalf("Resolve(tag) type = %T, want ref.Detached", resolvedTag)
+		}
+		if tagDet.ID != tagID {
+			t.Fatalf("Resolve(tag) id = %s, want %s", tagDet.ID, tagID)
+		}
+		if tagDet.Peeled == nil {
+			t.Fatalf("Resolve(tag) peeled = nil, want commit")
+		}
+		if *tagDet.Peeled != commitID {
+			t.Fatalf("Resolve(tag) peeled = %s, want %s", *tagDet.Peeled, commitID)
+		}
+
+		fullTag, err := store.ResolveFully("refs/tags/v1.0.0")
+		if err != nil {
+			t.Fatalf("ResolveFully(tag): %v", err)
+		}
+		if fullTag.ID != tagDet.ID {
+			t.Fatalf("ResolveFully(tag) id = %s, want %s", fullTag.ID, tagDet.ID)
+		}
+
+		if _, err := store.Resolve("refs/heads/does-not-exist"); !errors.Is(err, refstore.ErrReferenceNotFound) {
+			t.Fatalf("Resolve(not-found) error = %v", err)
+		}
+	})
+}
+
+func TestPackedListAndShorten(t *testing.T) {
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) {
+		testRepo := testgit.NewBareRepo(t, algo)
+		_, _, commitID := testRepo.MakeCommit(t, "packed refs list commit")
+		testRepo.UpdateRef(t, "refs/heads/main", commitID)
+		testRepo.UpdateRef(t, "refs/tags/main", commitID)
+		testRepo.UpdateRef(t, "refs/remotes/origin/main", commitID)
+		testRepo.PackRefs(t, "--all", "--prune")
+
+		store := openPackedRefStoreFromRepo(t, testRepo.Dir(), algo)
+
+		all, err := store.List("")
+		if err != nil {
+			t.Fatalf("List(all): %v", err)
+		}
+		allNames := make([]string, 0, len(all))
+		for _, entry := range all {
+			allNames = append(allNames, entry.Name())
+		}
+		slices.Sort(allNames)
+		wantAll := []string{"refs/heads/main", "refs/remotes/origin/main", "refs/tags/main"}
+		if !slices.Equal(allNames, wantAll) {
+			t.Fatalf("List(all) names = %v, want %v", allNames, wantAll)
+		}
+
+		filtered, err := store.List("refs/heads/*")
+		if err != nil {
+			t.Fatalf("List(pattern): %v", err)
+		}
+		if len(filtered) != 1 || filtered[0].Name() != "refs/heads/main" {
+			t.Fatalf("List(refs/heads/*) = %v, want refs/heads/main only", filtered)
+		}
+
+		short, err := store.Shorten("refs/heads/main")
+		if err != nil {
+			t.Fatalf("Shorten(main): %v", err)
+		}
+		if short != "heads/main" {
+			t.Fatalf("Shorten(main) = %q, want %q", short, "heads/main")
+		}
+
+		if _, err := store.Shorten("refs/heads/does-not-exist"); !errors.Is(err, refstore.ErrReferenceNotFound) {
+			t.Fatalf("Shorten(not-found) error = %v", err)
+		}
+	})
+}
+
+func TestPackedParseErrors(t *testing.T) {
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) {
+		cases := []struct {
+			name string
+			data string
+		}{
+			{
+				name: "peeled without ref",
+				data: "^" + stringsOfLen("0", algo.HexLen()) + "\n",
+			},
+			{
+				name: "invalid entry",
+				data: "not-a-valid-line\n",
+			},
+			{
+				name: "duplicate ref",
+				data: stringsOfLen("0", algo.HexLen()) + " refs/heads/main\n" +
+					stringsOfLen("1", algo.HexLen()) + " refs/heads/main\n",
+			},
+		}
+
+		for _, tt := range cases {
+			t.Run(tt.name, func(t *testing.T) {
+				if _, err := packed.New(bytes.NewBufferString(tt.data), algo); err == nil {
+					t.Fatalf("packed.New expected parse error")
+				}
+			})
+		}
+	})
+}
+
+func TestPackedNewValidation(t *testing.T) {
+	if _, err := packed.New(bytes.NewReader(nil), objectid.AlgorithmUnknown); !errors.Is(err, objectid.ErrInvalidAlgorithm) {
+		t.Fatalf("packed.New invalid algorithm error = %v", err)
+	}
+	if _, err := packed.New(nil, objectid.AlgorithmSHA1); err == nil {
+		t.Fatalf("packed.New nil reader expected error")
+	}
+}
+
+func stringsOfLen(ch string, n int) string {
+	return string(bytes.Repeat([]byte(ch), n))
+}