Artifact [8db423672f]

Artifact 8db423672fd0da0ac6dabe1971b697ec41b5dfb71206d251ffb0fbe155b639be:

• File internal/checkout/update_test.go — part of check-in [a71bf662ee] at 2026-10-18 20:59:23 on branch main — fix(checkout): record and trust vfile.mtime as fossil does (#444)

  * fix(checkout): record and trust vfile.mtime as fossil does

  go-libfossil wrote vfile.mtime = 0 everywhere and hashed every file on every scan, so it and fossil rehashed a go-libfossil checkout on every command.

  The scan is now fossil's vfile_check_signature: a file whose size matches its artifact (blob.size of mrid) and whose mtime matches vfile.mtime is taken as unchanged without being read, unless ScanHash is given or the mtime-changes setting is off; the scan stores the file's mtime in whole seconds and runs its updates in one transaction. Status, commit, merge, revert and extract use the default scan, as fossil's commands do.

  Mtimes are recorded where fossil records them: extract and update store the mtime of each file written with its artifact's content, an unchanged file keeps its mtime through LoadVFile (fossil's update transfer and in-place commit), committed files keep theirs, revert stores the restored file's, and SetMTime stores the time it gives. Undoing a rename drops the mtime, since the file was not checked.

  One deliberate difference: an mtime not older than the current second is stored as 0, so the next scan (ours or fossil's) hashes the file and an edit that keeps the size within that second is still seen. A stored 0 is never trusted.

  MemStorage now stamps each write with a new mtime from its own clock, as a filesystem does, so in-memory checkouts see same-size edits.

  Status on the sqlite repository's 2,220-file checkout: about 250 ms before, about 30 ms after.

  * test(checkout): pin the same-second guard against fossil

  A same-size edit in the second a file was scanned is committed, and fossil 2.28 reading a row the guard stored as 0 reports the edit. Both tests fail with the guard removed. The guard's comment and the CHANGELOG name it as the one deliberate difference from vfile_check_signature.

  * fix(checkout): record the mtime of each write as it happens

  Extract and update statted their files only after every file was written and vfile reloaded, so an edit in between was recorded as the written content. They now stat each file right after writing it, as fossil's vfile_to_disk does, and carry that mtime to the row. Revert and the new writtenMTime read the clock before the stat, as the scan does.

  A caller's Env without a Clock now gets the real clock, as Storage defaults to the OS; scans read it. The mtime-changes setting is read from the repository only: go-libfossil reads no global fossil settings, which the comment and CHANGELOG now say.

  New tests: an edit after extract's or update's write is seen, a stored 0 is never trusted, and a simulated clock at a realistic time drives the mtime fast path. (user: [email protected], size: 26098) [annotate] [blame] [check-ins using]

package checkout

import (
	"context"
	"errors"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"testing"
	"time"

	libfossil "github.com/danmestas/go-libfossil/internal/fsltype"
	"github.com/danmestas/go-libfossil/internal/manifest"
	"github.com/danmestas/go-libfossil/internal/repo"
	"github.com/danmestas/go-libfossil/simio"
)

// newTestRepoWithTwoCheckins creates a repo with two checkins.
// First checkin: hello.txt, src/main.go, README.md
// Second checkin: hello.txt modified, src/main.go unchanged, README.md unchanged, new.txt added
// Returns repo, rid1, rid2, cleanup.
func newTestRepoWithTwoCheckins(t *testing.T) (*repo.Repo, libfossil.FslID, libfossil.FslID, func()) {
	t.Helper()
	dir := t.TempDir()
	path := dir + "/test.fossil"
	r, err := repo.CreateWithEnv(path, "test", simio.RealEnv(), "")
	if err != nil {
		t.Fatal(err)
	}

	// First checkin
	rid1, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "hello.txt", Content: []byte("hello world\n")},
			{Name: "src/main.go", Content: []byte("package main\n")},
			{Name: "README.md", Content: []byte("# Test\n")},
		},
		Comment: "initial checkin",
		User:    "test",
		Parent:  0,
		Time:    time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		r.Close()
		t.Fatal(err)
	}

	// Second checkin — modify hello.txt, add new.txt
	rid2, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "hello.txt", Content: []byte("hello updated world\n")},
			{Name: "src/main.go", Content: []byte("package main\n")},
			{Name: "README.md", Content: []byte("# Test\n")},
			{Name: "new.txt", Content: []byte("new file\n")},
		},
		Comment: "second checkin",
		User:    "test",
		Parent:  rid1,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		r.Close()
		t.Fatal(err)
	}

	return r, rid1, rid2, func() { r.Close() }
}

func TestCalcUpdateVersion(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Checkout is at tip (rid2) after Create — CalcUpdateVersion should return 0.
	tip, err := co.CalcUpdateVersion()
	if err != nil {
		t.Fatal(err)
	}
	if tip != 0 {
		t.Fatalf("expected CalcUpdateVersion=0 at tip, got %d", tip)
	}

	// Set checkout to rid1 (the older version)
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	// Now CalcUpdateVersion should return rid2
	tip, err = co.CalcUpdateVersion()
	if err != nil {
		t.Fatal(err)
	}
	if tip != rid2 {
		t.Fatalf("CalcUpdateVersion = %d, want %d", tip, rid2)
	}
}

func TestUpdateLinear(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Set checkout to rid1
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	// Extract rid1 files to MemStorage
	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"

	if err := co.Extract(rid1, ExtractOpts{}); err != nil {
		t.Fatal("extract rid1:", err)
	}

	// Verify initial state
	data, err := mem.ReadFile("/checkout/hello.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "hello world\n" {
		t.Fatalf("before update: hello.txt = %q", data)
	}

	// Track changes via callback
	var changes []struct {
		name   string
		change UpdateChange
	}
	result, err := co.Update(UpdateOpts{
		TargetRID: rid2,
		Callback: func(name string, change UpdateChange) error {
			changes = append(changes, struct {
				name   string
				change UpdateChange
			}{name, change})
			return nil
		},
	})
	if err != nil {
		t.Fatal("Update:", err)
	}

	// A clean update must report no conflicted paths, and must report the
	// paths it actually touched — not merely how many.
	if len(result.Conflicted) != 0 {
		t.Fatalf("expected no conflicts, got %v", result.Conflicted)
	}
	if !containsPath(result.FilesWritten, "hello.txt") {
		t.Fatalf("expected FilesWritten to contain hello.txt, got %v", result.FilesWritten)
	}
	if !containsPath(result.FilesWritten, "new.txt") {
		t.Fatalf("expected FilesWritten to contain new.txt, got %v", result.FilesWritten)
	}

	// Verify hello.txt was updated
	data, err = mem.ReadFile("/checkout/hello.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "hello updated world\n" {
		t.Fatalf("after update: hello.txt = %q", data)
	}

	// Verify new.txt was added
	data, err = mem.ReadFile("/checkout/new.txt")
	if err != nil {
		t.Fatal("new.txt not found:", err)
	}
	if string(data) != "new file\n" {
		t.Fatalf("new.txt = %q", data)
	}

	// Verify unchanged files still present
	data, err = mem.ReadFile("/checkout/src/main.go")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "package main\n" {
		t.Fatalf("src/main.go = %q", data)
	}

	// Verify checkout version updated
	curRID, _, err := co.Version()
	if err != nil {
		t.Fatal(err)
	}
	if curRID != rid2 {
		t.Fatalf("after update: version RID = %d, want %d", curRID, rid2)
	}

	// Verify callbacks fired for changed files
	if len(changes) < 2 {
		t.Fatalf("expected at least 2 change callbacks, got %d", len(changes))
	}

	// Check that we got an UpdateUpdated for hello.txt and UpdateAdded for new.txt
	foundUpdated := false
	foundAdded := false
	for _, ch := range changes {
		if ch.name == "hello.txt" && ch.change == UpdateUpdated {
			foundUpdated = true
		}
		if ch.name == "new.txt" && ch.change == UpdateAdded {
			foundAdded = true
		}
	}
	if !foundUpdated {
		t.Error("expected UpdateUpdated callback for hello.txt")
	}
	if !foundAdded {
		t.Error("expected UpdateAdded callback for new.txt")
	}
}

func TestUpdateNoChanges(t *testing.T) {
	r, _, _, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Checkout is already at tip — Update should be a no-op
	result, err := co.Update(UpdateOpts{})
	if err != nil {
		t.Fatal("Update at tip should succeed:", err)
	}
	if len(result.Conflicted) != 0 || len(result.FilesWritten) != 0 || len(result.FilesRemoved) != 0 {
		t.Fatalf("expected empty result for no-op update, got %+v", result)
	}
}

func TestUpdateObserver(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Set to rid1
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"

	// Extract first so files exist
	if err := co.Extract(rid1, ExtractOpts{}); err != nil {
		t.Fatal(err)
	}

	// Install recording observer
	type event struct{ name string }
	var events []event
	obs := &testObserver{
		onExtractStarted: func(ctx context.Context, e ExtractStart) context.Context {
			if e.Operation != "update" {
				t.Errorf("expected operation=update, got %s", e.Operation)
			}
			if e.TargetRID != rid2 {
				t.Errorf("expected target=%d, got %d", rid2, e.TargetRID)
			}
			events = append(events, event{"started"})
			return ctx
		},
		onExtractFileCompleted: func(ctx context.Context, name string, change UpdateChange) {
			events = append(events, event{"file:" + name})
		},
		onExtractCompleted: func(ctx context.Context, e ExtractEnd) {
			if e.Operation != "update" {
				t.Errorf("expected operation=update, got %s", e.Operation)
			}
			events = append(events, event{"completed"})
		},
	}
	co.obs = obs

	if _, err := co.Update(UpdateOpts{TargetRID: rid2}); err != nil {
		t.Fatal(err)
	}

	if len(events) < 3 { // started + at least 1 file + completed
		t.Fatalf("expected at least 3 events, got %d: %v", len(events), events)
	}
	if events[0].name != "started" {
		t.Fatalf("first event = %s, want started", events[0].name)
	}
	if events[len(events)-1].name != "completed" {
		t.Fatalf("last event = %s, want completed", events[len(events)-1].name)
	}
}

func TestUpdateDryRun(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Set to rid1
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"

	// Extract rid1 files
	if err := co.Extract(rid1, ExtractOpts{}); err != nil {
		t.Fatal(err)
	}

	// DryRun update — should NOT modify files on disk
	var callbackCount int
	_, err = co.Update(UpdateOpts{
		TargetRID: rid2,
		DryRun:    true,
		Callback: func(name string, change UpdateChange) error {
			callbackCount++
			return nil
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// hello.txt should still have old content (dry run)
	data, err := mem.ReadFile("/checkout/hello.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "hello world\n" {
		t.Fatalf("dry run should not modify hello.txt, got %q", data)
	}

	// new.txt should NOT exist (dry run)
	if _, err := mem.ReadFile("/checkout/new.txt"); err == nil {
		t.Fatal("dry run should not create new.txt")
	}

	// But callbacks should have fired
	if callbackCount == 0 {
		t.Fatal("expected callbacks during dry run")
	}
}

func TestUpdateWithFileRemoval(t *testing.T) {
	// Create a repo where the second checkin removes a file.
	dir := t.TempDir()
	path := dir + "/test.fossil"
	r, err := repo.CreateWithEnv(path, "test", simio.RealEnv(), "")
	if err != nil {
		t.Fatal(err)
	}
	defer r.Close()

	// First checkin: three files.
	rid1, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "keep.txt", Content: []byte("keep\n")},
			{Name: "remove.txt", Content: []byte("bye\n")},
		},
		Comment: "initial",
		User:    "test",
		Parent:  0,
		Time:    time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	// Second checkin: remove.txt omitted.
	rid2, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "keep.txt", Content: []byte("keep\n")},
		},
		Comment: "remove file",
		User:    "test",
		Parent:  rid1,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	// Create checkout at rid1.
	ckDir := t.TempDir()
	co, err := Create(r, ckDir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Point checkout to rid1.
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	r.DB().QueryRow(
		"SELECT uuid FROM blob WHERE rid=?", rid1,
	).Scan(&uuid1)
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{
		Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{},
	}
	co.dir = "/checkout"
	if err := co.Extract(rid1, ExtractOpts{Force: true}); err != nil {
		t.Fatal(err)
	}

	// Verify remove.txt exists before update.
	if _, err := mem.ReadFile("/checkout/remove.txt"); err != nil {
		t.Fatal("remove.txt should exist before update:", err)
	}

	// Update to rid2.
	result, err := co.Update(UpdateOpts{TargetRID: rid2})
	if err != nil {
		t.Fatal(err)
	}
	if !containsPath(result.FilesRemoved, "remove.txt") {
		t.Fatalf("expected FilesRemoved to contain remove.txt, got %v", result.FilesRemoved)
	}

	// remove.txt should be deleted from Storage.
	if _, err := mem.ReadFile("/checkout/remove.txt"); err == nil {
		t.Fatal("remove.txt should be deleted after update")
	}

	// keep.txt should still exist.
	data, err := mem.ReadFile("/checkout/keep.txt")
	if err != nil {
		t.Fatal("keep.txt not found:", err)
	}
	if string(data) != "keep\n" {
		t.Fatalf("keep.txt = %q, want %q", data, "keep\n")
	}

	_ = rid2 // used above
}

func TestUpdateSetMTime(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Set checkout to rid1.
	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1)
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"

	if err := co.Extract(rid1, ExtractOpts{}); err != nil {
		t.Fatal("extract:", err)
	}

	// Update to rid2 with SetMTime.
	if _, err := co.Update(UpdateOpts{TargetRID: rid2, SetMTime: true}); err != nil {
		t.Fatal("update:", err)
	}

	// hello.txt was modified in rid2 — should have rid2's checkin mtime (2026-01-02).
	info, err := mem.Stat("/checkout/hello.txt")
	if err != nil {
		t.Fatal("stat hello.txt:", err)
	}
	mtime := info.ModTime()
	if mtime.IsZero() {
		t.Fatal("mtime should not be zero when SetMTime is true")
	}
	// rid2 timestamp is 2026-01-02.
	expected := time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC)
	if !mtime.Equal(expected) {
		t.Fatalf("hello.txt mtime = %v, want %v", mtime, expected)
	}

	// new.txt was added in rid2 — should also have rid2's mtime.
	info2, err := mem.Stat("/checkout/new.txt")
	if err != nil {
		t.Fatal("stat new.txt:", err)
	}
	if !info2.ModTime().Equal(expected) {
		t.Fatalf("new.txt mtime = %v, want %v", info2.ModTime(), expected)
	}
}

func TestUpdateSetMTimeFalse(t *testing.T) {
	r, rid1, rid2, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1)
	setVVar(co.db, "checkout-hash", uuid1)

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"

	co.Extract(rid1, ExtractOpts{})

	// Update WITHOUT SetMTime.
	if _, err := co.Update(UpdateOpts{TargetRID: rid2, SetMTime: false}); err != nil {
		t.Fatal("update:", err)
	}

	info, err := mem.Stat("/checkout/hello.txt")
	if err != nil {
		t.Fatal("stat:", err)
	}
	// The write's own time, not the check-in's.
	if info.ModTime().Equal(time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC)) {
		t.Fatalf("mtime set to the check-in time when SetMTime is false: %v", info.ModTime())
	}
}

// itoa is a helper to avoid importing strconv in tests.
func itoa(n int64) string {
	return strconv.FormatInt(n, 10)
}

// containsPath reports whether paths contains name.
func containsPath(paths []string, name string) bool {
	for _, p := range paths {
		if p == name {
			return true
		}
	}
	return false
}

// TestUpdateResultPathsAreSorted builds an update touching four files whose
// names are deliberately not in the order the underlying map would build
// them (allNames is a map[string]bool; Go randomizes iteration over it).
// Two files conflict (alpha.txt, zeta.txt) and two are clean additions
// (new_a.txt, new_z.txt). Every returned slice must come back sorted
// regardless of iteration order, so a caller can use reflect.DeepEqual or a
// golden file against the result instead of getting an intermittently
// ordered list.
func TestUpdateResultPathsAreSorted(t *testing.T) {
	dir := t.TempDir()
	path := dir + "/test.fossil"
	r, err := repo.CreateWithEnv(path, "test", simio.RealEnv(), "")
	if err != nil {
		t.Fatal(err)
	}
	defer r.Close()

	ridBase, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "zeta.txt", Content: []byte("original\n")},
			{Name: "alpha.txt", Content: []byte("original\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
		},
		Comment: "base",
		User:    "test",
		Parent:  0,
		Time:    time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	ridA, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "zeta.txt", Content: []byte("local version\n")},
			{Name: "alpha.txt", Content: []byte("local version\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
		},
		Comment: "branch A",
		User:    "test",
		Parent:  ridBase,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	// Branch B: conflicting edits to zeta.txt/alpha.txt, plus two brand-new
	// files that will be clean UpdateAdded entries in FilesWritten.
	ridB, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "zeta.txt", Content: []byte("remote version\n")},
			{Name: "alpha.txt", Content: []byte("remote version\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
			{Name: "new_z.txt", Content: []byte("new\n")},
			{Name: "new_a.txt", Content: []byte("new\n")},
		},
		Comment: "branch B",
		User:    "test",
		Parent:  ridBase,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	ckDir := t.TempDir()
	co, err := Create(r, ckDir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	if err := setVVar(co.db, "checkout", itoa(int64(ridA))); err != nil {
		t.Fatal(err)
	}
	var uuidA string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", ridA).Scan(&uuidA); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuidA); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"
	if err := co.Extract(ridA, ExtractOpts{}); err != nil {
		t.Fatal(err)
	}

	result, err := co.Update(UpdateOpts{TargetRID: ridB})
	if err != nil {
		t.Fatalf("Update with conflicts should still succeed (err==nil): %v", err)
	}

	wantConflicted := []string{"alpha.txt", "zeta.txt"}
	if !reflect.DeepEqual(result.Conflicted, wantConflicted) {
		t.Fatalf("Conflicted = %v, want sorted %v", result.Conflicted, wantConflicted)
	}

	wantWritten := []string{"alpha.txt", "new_a.txt", "new_z.txt", "zeta.txt"}
	if !reflect.DeepEqual(result.FilesWritten, wantWritten) {
		t.Fatalf("FilesWritten = %v, want sorted %v", result.FilesWritten, wantWritten)
	}

	if !sort.StringsAreSorted(result.FilesWritten) {
		t.Fatalf("FilesWritten not sorted: %v", result.FilesWritten)
	}
	if !sort.StringsAreSorted(result.Conflicted) {
		t.Fatalf("Conflicted not sorted: %v", result.Conflicted)
	}
}

// TestUpdateConflictSurfacesPaths builds a genuine fork — two checkins with
// the same parent, both editing the same line of the same file — and updates
// across it. The three-way merge cannot resolve the overlapping edit cleanly,
// so it writes conflict markers into conflict.txt. The update must still
// report err == nil (this is a successful update — the working tree is
// usable, just not clean) and must list conflict.txt in Conflicted.
func TestUpdateConflictSurfacesPaths(t *testing.T) {
	dir := t.TempDir()
	path := dir + "/test.fossil"
	r, err := repo.CreateWithEnv(path, "test", simio.RealEnv(), "")
	if err != nil {
		t.Fatal(err)
	}
	defer r.Close()

	// Ancestor: base content both sides will diverge from.
	ridBase, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "conflict.txt", Content: []byte("original\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
		},
		Comment: "base",
		User:    "test",
		Parent:  0,
		Time:    time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	// Leaf A ("current"): edits conflict.txt one way.
	ridA, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "conflict.txt", Content: []byte("local version\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
		},
		Comment: "branch A",
		User:    "test",
		Parent:  ridBase,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	// Leaf B ("target"): edits conflict.txt a different, incompatible way.
	ridB, _, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files: []manifest.File{
			{Name: "conflict.txt", Content: []byte("remote version\n")},
			{Name: "stable.txt", Content: []byte("stable\n")},
		},
		Comment: "branch B",
		User:    "test",
		Parent:  ridBase,
		Time:    time.Date(2026, 1, 2, 0, 0, 0, 0, time.UTC),
	})
	if err != nil {
		t.Fatal(err)
	}

	ckDir := t.TempDir()
	co, err := Create(r, ckDir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	// Point the checkout at leaf A.
	if err := setVVar(co.db, "checkout", itoa(int64(ridA))); err != nil {
		t.Fatal(err)
	}
	var uuidA string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", ridA).Scan(&uuidA); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuidA); err != nil {
		t.Fatal(err)
	}

	mem := simio.NewMemStorage()
	co.env = &simio.Env{Storage: mem, Clock: simio.RealClock{}, Rand: simio.CryptoRand{}}
	co.dir = "/checkout"
	if err := co.Extract(ridA, ExtractOpts{}); err != nil {
		t.Fatal(err)
	}

	// Update from leaf A to leaf B — this must 3-way merge conflict.txt
	// against the common ancestor (ridBase) and fail to merge cleanly.
	result, err := co.Update(UpdateOpts{TargetRID: ridB})
	if err != nil {
		t.Fatalf("Update with conflict should still succeed (err==nil): %v", err)
	}

	if len(result.Conflicted) != 1 || result.Conflicted[0] != "conflict.txt" {
		t.Fatalf("expected Conflicted=[conflict.txt], got %v", result.Conflicted)
	}
	if !containsPath(result.FilesWritten, "conflict.txt") {
		t.Fatalf("expected FilesWritten to contain conflict.txt, got %v", result.FilesWritten)
	}

	// The conflicted file must actually contain conflict markers on disk —
	// that's the entire point of the Conflicted field.
	data, err := mem.ReadFile("/checkout/conflict.txt")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(string(data), "<<<<<<<") {
		t.Fatalf("expected conflict markers in conflict.txt, got %q", data)
	}
}

// TestUpdateFailureIsDistinguishableFromConflict confirms a genuine failure
// (target checkin does not exist) returns a non-nil error, distinct from the
// conflicted-but-successful case above.
func TestUpdateFailureIsDistinguishableFromConflict(t *testing.T) {
	r, rid1, _, cleanup := newTestRepoWithTwoCheckins(t)
	defer cleanup()

	dir := t.TempDir()
	co, err := Create(r, dir, CreateOpts{})
	if err != nil {
		t.Fatal(err)
	}
	defer co.Close()

	if err := setVVar(co.db, "checkout", itoa(int64(rid1))); err != nil {
		t.Fatal(err)
	}
	var uuid1 string
	if err := r.DB().QueryRow("SELECT uuid FROM blob WHERE rid=?", rid1).Scan(&uuid1); err != nil {
		t.Fatal(err)
	}
	if err := setVVar(co.db, "checkout-hash", uuid1); err != nil {
		t.Fatal(err)
	}

	_, err = co.Update(UpdateOpts{TargetRID: 999999})
	if err == nil {
		t.Fatal("expected error for nonexistent target RID, got nil")
	}
}

// TestUpdateRefusesMissingContentBeforeWriting pins that Update checks the
// target's content is all present before touching disk, as fossil's update
// does (#231): otherwise it could write some files and then fail, leaving
// disk on the target while the checkout still records the old version.
func TestUpdateRefusesMissingContentBeforeWriting(t *testing.T) {
	co, mem, rid1, rid2 := newCheckoutAtFirstOfTwo(t)
	phantomize(t, co, rid2, "new.txt")

	_, err := co.Update(UpdateOpts{TargetRID: rid2})
	if !errors.Is(err, errMissingContent) {
		t.Fatalf("Update = %v, want errMissingContent", err)
	}
	data, err := mem.ReadFile("/checkout/hello.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "hello world\n" {
		t.Fatalf("hello.txt = %q, Update wrote before refusing", data)
	}
	if vid := mustVersion(t, co); vid != rid1 {
		t.Fatalf("Version = %d after refusal, want %d", vid, rid1)
	}
}

// A negative target is a caller's mistake, reported as an error rather than
// a panic: it arrives through the public UpdateOpts.TargetRID.
func TestUpdateRejectsNegativeTarget(t *testing.T) {
	co, _, _, _ := newCheckoutAtFirstOfTwo(t) // only the checkout matters here
	if _, err := co.Update(UpdateOpts{TargetRID: -1}); err == nil {
		t.Fatal("Update with a negative target succeeded")
	}
}

// A dry-run Update leaves the checkout on its version (#236).
func TestUpdateDryRunKeepsVersion(t *testing.T) {
	co, mem, rid1, rid2 := newCheckoutAtFirstOfTwo(t)

	if _, err := co.Update(UpdateOpts{TargetRID: rid2, DryRun: true}); err != nil {
		t.Fatalf("dry-run update: %v", err)
	}
	if vid := mustVersion(t, co); vid != rid1 {
		t.Fatalf("Version = %d after a dry-run update, want %d", vid, rid1)
	}
	data, err := mem.ReadFile("/checkout/hello.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(data) != "hello world\n" {
		t.Fatalf("hello.txt = %q after a dry-run update, want it untouched", data)
	}
}