4 files changed, 217 insertions, 10 deletions
diff --git a/test/internal/testsuite/fs.go b/test/internal/testsuite/fs.go
new file mode 100644
index 00000000..9acd24b6
--- /dev/null
+++ b/test/internal/testsuite/fs.go
@@ -0,0 +1,129 @@
+package testsuite
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	// ErrFSBadLength is returned by [FS.Compare] for a directory with an
+	// unexpected amount of dents.
+	ErrFSBadLength = errors.New("bad dir length")
+	// ErrFSBadData is returned by [FS.Compare] for a file with unexpected
+	// contents.
+	ErrFSBadData = errors.New("data differs")
+	// ErrFSBadMode is returned by [FS.Compare] for an entry with unexpected
+	// mode.
+	ErrFSBadMode = errors.New("mode differs")
+	// ErrFSInvalidEnt is returned by [FS.Compare] if an invalid [FS] is visited.
+	ErrFSInvalidEnt = errors.New("invalid entry condition")
+)
+
+// FS represents part of a filesystem hierarchy.
+type FS struct {
+	// Expected mode of corresponding entry.
+	Mode fs.FileMode `json:"mode"`
+	// Expected directory contents. The directory is not descended if Dir is nil.
+	Dir map[string]*FS `json:"dir"`
+	// Expected file contents. The file is not read if Data is nil.
+	Data *string `json:"data"`
+}
+
+// dprintf calls printf if it is non-nil.
+func dprintf(printf func(format string, a ...any), format string, a ...any) {
+	if printf == nil {
+		return
+	}
+	printf(format, a...)
+}
+
+// printDir prints a failed [FS.Compare] directory.
+func printDir(
+	printf func(format string, a ...any),
+	prefix string,
+	dir []fs.DirEntry,
+) {
+	names := make([]string, len(dir))
+	for i, ent := range dir {
+		name := ent.Name()
+		if ent.IsDir() {
+			name += "/"
+		}
+		names[i] = fmt.Sprintf("%q", name)
+	}
+	dprintf(printf, "[FAIL] d %s: %s", prefix, strings.Join(names, " "))
+}
+
+// Compare compares the contents of prefix against the hierarchy described by s.
+func (s *FS) Compare(
+	printf func(format string, a ...any),
+	prefix string,
+	e fs.FS,
+) error {
+	if s.Data != nil {
+		if s.Dir != nil {
+			panic("invalid state")
+		}
+		panic("invalid compare call")
+	}
+
+	if s.Dir == nil {
+		dprintf(printf, "[ OK ] s %s", prefix)
+		return nil
+	}
+
+	var dir []fs.DirEntry
+	if d, err := fs.ReadDir(e, prefix); err != nil {
+		return err
+	} else if len(d) != len(s.Dir) {
+		printDir(printf, prefix, d)
+		return ErrFSBadLength
+	} else {
+		dir = d
+	}
+
+	for _, got := range dir {
+		name := got.Name()
+
+		if want, ok := s.Dir[name]; !ok {
+			printDir(printf, prefix, dir)
+			return fs.ErrNotExist
+		} else if want.Dir != nil && !got.IsDir() {
+			printDir(printf, prefix, dir)
+			return ErrFSInvalidEnt
+		} else {
+			name = filepath.Join(prefix, name)
+
+			if fi, err := got.Info(); err != nil {
+				return err
+			} else if fi.Mode() != want.Mode {
+				dprintf(printf, "[FAIL] m %s: %#o, want %#o",
+					name, uint32(fi.Mode()), uint32(want.Mode))
+				return ErrFSBadMode
+			}
+
+			if want.Data != nil {
+				if want.Dir != nil {
+					panic("invalid state")
+				}
+				if v, err := fs.ReadFile(e, name); err != nil {
+					return err
+				} else if string(v) != *want.Data {
+					dprintf(printf,
+						"[FAIL] f %s\n\t got: %s\n\twant: %s",
+						name, v, *want.Data,
+					)
+					return ErrFSBadData
+				}
+				dprintf(printf, "[ OK ] f %s", name)
+			} else if err := want.Compare(printf, name, e); err != nil {
+				return err
+			}
+		}
+	}
+	dprintf(printf, "[ OK ] d %s", prefix)
+	return nil
+}
diff --git a/test/internal/testsuite/fs_test.go b/test/internal/testsuite/fs_test.go
new file mode 100644
index 00000000..5c93bb46
--- /dev/null
+++ b/test/internal/testsuite/fs_test.go
@@ -0,0 +1,85 @@
+package testsuite_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io/fs"
+	"testing"
+	"testing/fstest"
+
+	"hakurei.app/test/internal/testsuite"
+)
+
+func TestCompare(t *testing.T) {
+	var (
+		fsPasswdSample = "u0_a20:x:65534:65534:Hakurei:/var/lib/persist/module/hakurei/u0/a20:/run/current-system/sw/bin/zsh"
+		fsGroupSample  = "hakurei:x:65534:"
+	)
+
+	testCases := []struct {
+		name string
+
+		sample  fstest.MapFS
+		want    *testsuite.FS
+		wantOut string
+		wantErr error
+	}{
+		{"skip", fstest.MapFS{}, &testsuite.FS{}, "[ OK ] s .\x00", nil},
+		{"simple pass", fstest.MapFS{".hakurei": {Mode: 0x800001ed}},
+			&testsuite.FS{Dir: map[string]*testsuite.FS{".hakurei": {Mode: 0x800001ed}}},
+			"[ OK ] s .hakurei\x00[ OK ] d .\x00", nil},
+		{"bad length", fstest.MapFS{".hakurei": {Mode: 0x800001ed}},
+			&testsuite.FS{Dir: make(map[string]*testsuite.FS)},
+			"[FAIL] d .: \".hakurei/\"\x00", testsuite.ErrFSBadLength},
+		{"top level bad mode", fstest.MapFS{".hakurei": {Mode: 0x800001ed}},
+			&testsuite.FS{Dir: map[string]*testsuite.FS{".hakurei": {Mode: 0xdeadbeef}}},
+			"[FAIL] m .hakurei: 020000000755, want 033653337357\x00", testsuite.ErrFSBadMode},
+		{"invalid entry condition", fstest.MapFS{"test": {Data: []byte{'0'}, Mode: 0644}},
+			&testsuite.FS{Dir: map[string]*testsuite.FS{"test": {Dir: make(map[string]*testsuite.FS)}}},
+			"[FAIL] d .: \"test\"\x00", testsuite.ErrFSInvalidEnt},
+		{"nonexistent", fstest.MapFS{"test": {Data: []byte{'0'}, Mode: 0644}},
+			&testsuite.FS{Dir: map[string]*testsuite.FS{".test": {}}},
+			"[FAIL] d .: \"test\"\x00", fs.ErrNotExist},
+		{"file", fstest.MapFS{"etc": {Mode: 0x800001c0},
+			"etc/passwd": {Data: []byte(fsPasswdSample), Mode: 0644},
+			"etc/group":  {Data: []byte(fsGroupSample), Mode: 0644},
+		}, &testsuite.FS{Dir: map[string]*testsuite.FS{"etc": {Mode: 0x800001c0, Dir: map[string]*testsuite.FS{
+			"passwd": {Mode: 0x1a4, Data: &fsPasswdSample},
+			"group":  {Mode: 0x1a4, Data: &fsGroupSample},
+		}}}}, "[ OK ] f etc/group\x00[ OK ] f etc/passwd\x00[ OK ] d etc\x00[ OK ] d .\x00", nil},
+		{"file differ", fstest.MapFS{"etc": {Mode: 0x800001c0},
+			"etc/passwd": {Data: []byte(fsPasswdSample), Mode: 0644},
+			"etc/group":  {Data: []byte(fsGroupSample), Mode: 0644},
+		}, &testsuite.FS{Dir: map[string]*testsuite.FS{"etc": {Mode: 0x800001c0, Dir: map[string]*testsuite.FS{
+			"passwd": {Mode: 0x1a4, Data: &fsGroupSample},
+			"group":  {Mode: 0x1a4, Data: &fsGroupSample},
+		}}}}, "[ OK ] f etc/group\x00[FAIL] f etc/passwd\n\t got: u0_a20:x:65534:65534:Hakurei:/var/lib/persist/module/hakurei/u0/a20:/run/current-system/sw/bin/zsh\n\twant: hakurei:x:65534:\x00", testsuite.ErrFSBadData},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var buf bytes.Buffer
+
+			err := tc.want.Compare(
+				func(format string, a ...any) {
+					_, _ = fmt.Fprintf(&buf, format+"\x00", a...)
+				},
+				".", tc.sample,
+			)
+			if !errors.Is(err, tc.wantErr) {
+				t.Errorf(
+					"Compare: error = %v; wantErr %v",
+					err, tc.wantErr,
+				)
+			}
+
+			if buf.String() != tc.wantOut {
+				t.Errorf(
+					"Compare: output %q; want %q",
+					&buf, tc.wantOut,
+				)
+			}
+		})
+	}
+}
diff --git a/test/internal/testsuite/testsuite.go b/test/internal/testsuite/testsuite.go
index ef250ec8..6b4cd717 100644
--- a/test/internal/testsuite/testsuite.go
+++ b/test/internal/testsuite/testsuite.go
@@ -11,18 +11,8 @@ import (
 	"os/signal"
 	"os/user"
 	"syscall"
-	"testing"
 )
 
-func init() {
-	if testing.Testing() {
-		return
-	}
-
-	log.SetFlags(0)
-	log.SetPrefix("testsuite: ")
-}
-
 // ReceiveSignals blocks until a termination signal arrives, and terminates.
 func ReceiveSignals() {
 	s := make(chan os.Signal, 3)
diff --git a/test/internal/testsuite/testsuite_root.go b/test/internal/testsuite/testsuite_root.go
index 830e272c..11f503ef 100644
--- a/test/internal/testsuite/testsuite_root.go
+++ b/test/internal/testsuite/testsuite_root.go
@@ -11,4 +11,7 @@ func init() {
 	if os.Geteuid() != 0 {
 		log.Fatal("this program must run as root")
 	}
+
+	log.SetFlags(0)
+	log.SetPrefix("testsuite: ")
 }