reachability: Refactor v0.1.41

1 files changed, 388 insertions, 0 deletions

diff --git a/reachability/integration_test.go b/reachability/integration_test.go
new file mode 100644
index 00000000..10668006
--- /dev/null
+++ b/reachability/integration_test.go
@@ -0,0 +1,388 @@
+package reachability_test
+
+import (
+	"errors"
+	"fmt"
+	"maps"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+
+	"codeberg.org/lindenii/furgit/internal/testgit"
+	"codeberg.org/lindenii/furgit/objectid"
+	"codeberg.org/lindenii/furgit/reachability"
+	"codeberg.org/lindenii/furgit/repository"
+)
+
+func TestWalkCommitsMatchesGitRevList(t *testing.T) {
+	t.Parallel()
+
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) { //nolint:thelper
+		testRepo := testgit.NewRepo(t, testgit.RepoOptions{
+			ObjectFormat: algo,
+			Bare:         true,
+			RefFormat:    "files",
+		})
+
+		_, tree1 := testRepo.MakeSingleFileTree(t, "base.txt", []byte("base\n"))
+		base := testRepo.CommitTree(t, tree1, "base")
+
+		_, tree2 := testRepo.MakeSingleFileTree(t, "left.txt", []byte("left\n"))
+		left := testRepo.CommitTree(t, tree2, "left", base)
+
+		_, tree3 := testRepo.MakeSingleFileTree(t, "right.txt", []byte("right\n"))
+		right := testRepo.CommitTree(t, tree3, "right", base)
+
+		_, tree4 := testRepo.MakeSingleFileTree(t, "merge.txt", []byte("merge\n"))
+		merge := testRepo.CommitTree(t, tree4, "merge", left, right)
+
+		tag1 := testRepo.TagAnnotated(t, "v1", merge, "v1")
+		tag2 := testRepo.TagAnnotated(t, "v2", tag1, "v2")
+
+		r := openReachabilityFromTestRepo(t, testRepo)
+		walk := r.Walk(
+			reachability.DomainCommits,
+			nil,
+			map[objectid.ObjectID]struct{}{merge: {}},
+		)
+		got := oidSetFromSeq(walk.Seq())
+		if err := walk.Err(); err != nil {
+			t.Fatalf("walk.Err(): %v", err)
+		}
+
+		want := gitRevListSet(t, testRepo, false, []objectid.ObjectID{merge}, nil)
+		if !maps.Equal(got, want) {
+			t.Fatalf("commit walk mismatch:\n got=%v\nwant=%v", sortedOIDStrings(got), sortedOIDStrings(want))
+		}
+
+		peelWalk := r.Walk(
+			reachability.DomainCommits,
+			nil,
+			map[objectid.ObjectID]struct{}{tag2: {}},
+		)
+		peelGot := oidSetFromSeq(peelWalk.Seq())
+		if err := peelWalk.Err(); err != nil {
+			t.Fatalf("peelWalk.Err(): %v", err)
+		}
+		wantWithTags := maps.Clone(want)
+		wantWithTags[tag1] = struct{}{}
+		wantWithTags[tag2] = struct{}{}
+		if !maps.Equal(peelGot, wantWithTags) {
+			t.Fatalf("tag-root commit walk mismatch:\n got=%v\nwant=%v", sortedOIDStrings(peelGot), sortedOIDStrings(wantWithTags))
+		}
+	})
+}
+
+func TestWalkObjectsMatchesGitRevListObjects(t *testing.T) {
+	t.Parallel()
+
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) { //nolint:thelper
+		testRepo := testgit.NewRepo(t, testgit.RepoOptions{
+			ObjectFormat: algo,
+			Bare:         true,
+			RefFormat:    "files",
+		})
+
+		aBlob := testRepo.HashObject(t, "blob", []byte("a\n"))
+		bBlob := testRepo.HashObject(t, "blob", []byte("b\n"))
+		nestedTree := testRepo.Mktree(t, fmt.Sprintf("100644 blob %s\tb.txt\n", bBlob))
+		rootTree := testRepo.Mktree(t,
+			fmt.Sprintf("100644 blob %s\ta.txt\n040000 tree %s\tdir\n", aBlob, nestedTree),
+		)
+		base := testRepo.CommitTree(t, rootTree, "base")
+
+		cBlob := testRepo.HashObject(t, "blob", []byte("c\n"))
+		tree2 := testRepo.Mktree(t, fmt.Sprintf("100644 blob %s\tc.txt\n", cBlob))
+		head := testRepo.CommitTree(t, tree2, "head", base)
+		tag := testRepo.TagAnnotated(t, "objtag", head, "objtag")
+
+		r := openReachabilityFromTestRepo(t, testRepo)
+		walk := r.Walk(
+			reachability.DomainObjects,
+			nil,
+			map[objectid.ObjectID]struct{}{head: {}},
+		)
+		got := oidSetFromSeq(walk.Seq())
+		if err := walk.Err(); err != nil {
+			t.Fatalf("walk.Err(): %v", err)
+		}
+
+		want := gitRevListSet(t, testRepo, true, []objectid.ObjectID{head}, nil)
+		if !maps.Equal(got, want) {
+			t.Fatalf("object walk mismatch:\n got=%v\nwant=%v", sortedOIDStrings(got), sortedOIDStrings(want))
+		}
+
+		peelWalk := r.Walk(
+			reachability.DomainObjects,
+			nil,
+			map[objectid.ObjectID]struct{}{tag: {}},
+		)
+		peelGot := oidSetFromSeq(peelWalk.Seq())
+		if err := peelWalk.Err(); err != nil {
+			t.Fatalf("peelWalk.Err(): %v", err)
+		}
+		wantFromTag := gitRevListSet(t, testRepo, true, []objectid.ObjectID{tag}, nil)
+		if !maps.Equal(peelGot, wantFromTag) {
+			t.Fatalf("tag-root object walk mismatch:\n got=%v\nwant=%v", sortedOIDStrings(peelGot), sortedOIDStrings(wantFromTag))
+		}
+
+		walkWithHave := r.Walk(
+			reachability.DomainObjects,
+			map[objectid.ObjectID]struct{}{base: {}},
+			map[objectid.ObjectID]struct{}{head: {}},
+		)
+		withHave := oidSetFromSeq(walkWithHave.Seq())
+		if err := walkWithHave.Err(); err != nil {
+			t.Fatalf("walkWithHave.Err(): %v", err)
+		}
+		if _, ok := withHave[base]; ok {
+			t.Fatalf("walk output unexpectedly contains have commit %s", base)
+		}
+	})
+}
+
+func TestIsAncestorMatchesGitMergeBase(t *testing.T) {
+	t.Parallel()
+
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) { //nolint:thelper
+		testRepo := testgit.NewRepo(t, testgit.RepoOptions{
+			ObjectFormat: algo,
+			Bare:         true,
+			RefFormat:    "files",
+		})
+
+		_, tree1 := testRepo.MakeSingleFileTree(t, "one.txt", []byte("one\n"))
+		c1 := testRepo.CommitTree(t, tree1, "c1")
+
+		_, tree2 := testRepo.MakeSingleFileTree(t, "two.txt", []byte("two\n"))
+		c2 := testRepo.CommitTree(t, tree2, "c2", c1)
+
+		_, tree3 := testRepo.MakeSingleFileTree(t, "three.txt", []byte("three\n"))
+		c3 := testRepo.CommitTree(t, tree3, "c3", c2)
+
+		tag := testRepo.TagAnnotated(t, "tip", c2, "tip")
+
+		r := openReachabilityFromTestRepo(t, testRepo)
+
+		got, err := r.IsAncestor(c1, tag)
+		if err != nil {
+			t.Fatalf("IsAncestor(c1, tag): %v", err)
+		}
+		if want := gitMergeBaseIsAncestor(t, testRepo, c1, c2); got != want {
+			t.Fatalf("IsAncestor(c1, tag)=%v, want %v", got, want)
+		}
+
+		got, err = r.IsAncestor(c3, c2)
+		if err != nil {
+			t.Fatalf("IsAncestor(c3, c2): %v", err)
+		}
+		if want := gitMergeBaseIsAncestor(t, testRepo, c3, c2); got != want {
+			t.Fatalf("IsAncestor(c3, c2)=%v, want %v", got, want)
+		}
+	})
+}
+
+func TestCheckConnectedMissingObject(t *testing.T) {
+	t.Parallel()
+
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) { //nolint:thelper
+		testRepo := testgit.NewRepo(t, testgit.RepoOptions{
+			ObjectFormat: algo,
+			Bare:         true,
+			RefFormat:    "files",
+		})
+
+		_, treeID, commitID := testRepo.MakeCommit(t, "missing")
+		if err := os.Remove(looseObjectPath(testRepo.Dir(), treeID)); err != nil {
+			t.Fatalf("remove tree object: %v", err)
+		}
+
+		r := openReachabilityFromTestRepo(t, testRepo)
+		err := r.CheckConnected(
+			reachability.DomainObjects,
+			nil,
+			map[objectid.ObjectID]struct{}{commitID: {}},
+		)
+		if err == nil {
+			t.Fatal("expected error")
+		}
+		var missing *reachability.ErrObjectMissing
+		if !errors.As(err, &missing) {
+			t.Fatalf("expected ErrObjectMissing, got %T (%v)", err, err)
+		}
+		if missing.OID != treeID {
+			t.Fatalf("missing oid = %s, want %s", missing.OID, treeID)
+		}
+	})
+}
+
+func TestWalkOnPackedOnlyRepo(t *testing.T) {
+	t.Parallel()
+
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) { //nolint:thelper
+		testRepo := testgit.NewRepo(t, testgit.RepoOptions{
+			ObjectFormat: algo,
+			Bare:         true,
+			RefFormat:    "files",
+		})
+
+		_, tree1 := testRepo.MakeSingleFileTree(t, "one.txt", []byte("one\n"))
+		c1 := testRepo.CommitTree(t, tree1, "one")
+		_, tree2 := testRepo.MakeSingleFileTree(t, "two.txt", []byte("two\n"))
+		c2 := testRepo.CommitTree(t, tree2, "two", c1)
+		testRepo.UpdateRef(t, "refs/heads/main", c2)
+		testRepo.SymbolicRef(t, "HEAD", "refs/heads/main")
+
+		testRepo.Repack(t, "-ad")
+		testRepo.Run(t, "prune-packed")
+
+		assertPackedOnly(t, testRepo.Dir())
+
+		r := openReachabilityFromTestRepo(t, testRepo)
+		walk := r.Walk(
+			reachability.DomainCommits,
+			nil,
+			map[objectid.ObjectID]struct{}{c2: {}},
+		)
+		got := oidSetFromSeq(walk.Seq())
+		if err := walk.Err(); err != nil {
+			t.Fatalf("walk.Err(): %v", err)
+		}
+		if _, ok := got[c2]; !ok {
+			t.Fatalf("walk output missing HEAD commit %s", c2)
+		}
+		if _, ok := got[c1]; !ok {
+			t.Fatalf("walk output missing parent commit %s", c1)
+		}
+	})
+}
+
+func openReachabilityFromTestRepo(t *testing.T, testRepo *testgit.TestRepo) *reachability.Reachability {
+	t.Helper()
+	root, err := os.OpenRoot(testRepo.Dir())
+	if err != nil {
+		t.Fatalf("os.OpenRoot: %v", err)
+	}
+	t.Cleanup(func() { _ = root.Close() })
+
+	repo, err := repository.Open(root)
+	if err != nil {
+		t.Fatalf("repository.Open: %v", err)
+	}
+	t.Cleanup(func() { _ = repo.Close() })
+
+	return reachability.New(repo.Objects())
+}
+
+func oidSetFromSeq(seq func(func(objectid.ObjectID) bool)) map[objectid.ObjectID]struct{} {
+	out := make(map[objectid.ObjectID]struct{})
+	seq(func(id objectid.ObjectID) bool {
+		out[id] = struct{}{}
+		return true
+	})
+	return out
+}
+
+func gitRevListSet(
+	t *testing.T,
+	testRepo *testgit.TestRepo,
+	includeObjects bool,
+	wants []objectid.ObjectID,
+	haves []objectid.ObjectID,
+) map[objectid.ObjectID]struct{} {
+	t.Helper()
+
+	args := []string{"rev-list"}
+	if includeObjects {
+		args = append(args, "--objects")
+	}
+	for _, want := range wants {
+		args = append(args, want.String())
+	}
+	if len(haves) > 0 {
+		args = append(args, "--not")
+		for _, have := range haves {
+			args = append(args, have.String())
+		}
+	}
+
+	out := testRepo.Run(t, args...)
+	set := make(map[objectid.ObjectID]struct{})
+	for line := range strings.SplitSeq(strings.TrimSpace(out), "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		tok := line
+		if i := strings.IndexByte(tok, ' '); i >= 0 {
+			tok = tok[:i]
+		}
+		id, err := objectid.ParseHex(testRepo.Algorithm(), tok)
+		if err != nil {
+			t.Fatalf("parse rev-list oid %q: %v", tok, err)
+		}
+		set[id] = struct{}{}
+	}
+	return set
+}
+
+func gitMergeBaseIsAncestor(t *testing.T, testRepo *testgit.TestRepo, a, b objectid.ObjectID) bool {
+	t.Helper()
+	// testgit.Run fatals on non-zero status, so we compare merge-base output.
+	mb := testRepo.Run(t, "merge-base", a.String(), b.String())
+	return mb == a.String()
+}
+
+func sortedOIDStrings(set map[objectid.ObjectID]struct{}) []string {
+	out := make([]string, 0, len(set))
+	for id := range set {
+		out = append(out, id.String())
+	}
+	slices.Sort(out)
+	return out
+}
+
+func looseObjectPath(repoDir string, id objectid.ObjectID) string {
+	hex := id.String()
+	return filepath.Join(repoDir, "objects", hex[:2], hex[2:])
+}
+
+func assertPackedOnly(t *testing.T, repoDir string) {
+	t.Helper()
+	objectsDir := filepath.Join(repoDir, "objects")
+
+	entries, err := os.ReadDir(objectsDir)
+	if err != nil {
+		t.Fatalf("ReadDir(objects): %v", err)
+	}
+	for _, entry := range entries {
+		name := entry.Name()
+		if name == "pack" || name == "info" {
+			continue
+		}
+		if len(name) == 2 && isHexDirName(name) {
+			subEntries, err := os.ReadDir(filepath.Join(objectsDir, name))
+			if err != nil {
+				t.Fatalf("ReadDir(objects/%s): %v", name, err)
+			}
+			if len(subEntries) != 0 {
+				t.Fatalf("found loose objects in %s", filepath.Join(objectsDir, name))
+			}
+		}
+	}
+}
+
+func isHexDirName(name string) bool {
+	if len(name) != 2 {
+		return false
+	}
+	for i := range 2 {
+		c := name[i]
+		if (c < '0' || c > '9') && (c < 'a' || c > 'f') {
+			return false
+		}
+	}
+	return true
+}