var Data = func() (entries []Entry) {
	fis := mustGet(fs.ReadDir(testdataFS, "testdata"))
	slices.SortFunc(fis, func(x, y fs.DirEntry) int { return strings.Compare(x.Name(), y.Name()) })
	for _, fi := range fis {
		var entry Entry

		words := strings.Split(strings.TrimSuffix(fi.Name(), ".json.gz"), "_")
		for i := range words {
			words[i] = strings.Title(words[i])
		}
		entry.Name = strings.Join(words, "")

		filePath := path.Join("testdata", fi.Name())
		f := mustGet(testdataFS.Open(filePath))
		defer f.Close()
		mustGet(f.(io.Seeker).Seek(-4, io.SeekEnd))
		b := mustGet(io.ReadAll(f))
		entry.Size = int(binary.LittleEndian.Uint32(b[:]))

		entry.Data = sync.OnceValue(func() []byte {
			b := mustGet(fs.ReadFile(testdataFS, filePath))
			zr := mustGet(gzip.NewReader(bytes.NewReader(b)))
			data := mustGet(io.ReadAll(zr))
			if len(data) != entry.Size {
				panic(fmt.Sprintf("size mismatch: got %d, want %d", len(data), entry.Size))
			}
			return data
		})

		switch entry.Name {
		case "CanadaGeometry":
			entry.New = func() any { return new(canadaRoot) }
		case "CitmCatalog":
			entry.New = func() any { return new(citmRoot) }
		case "GolangSource":
			entry.New = func() any { return new(golangRoot) }
		case "StringEscaped":
			entry.New = func() any { return new(stringRoot) }
		case "StringUnicode":
			entry.New = func() any { return new(stringRoot) }
		case "SyntheaFhir":
			entry.New = func() any { return new(syntheaRoot) }
		case "TwitterStatus":
			entry.New = func() any { return new(twitterRoot) }
		}

		entries = append(entries, entry)
	}
	return entries
}()

type CaseName struct {
	Name  string
	Where CasePos
}

type CasePos struct {
	// contains filtered or unexported fields
}

type Entry struct {
	Name string
	Size int
	Data func() []byte
	New  func() any // nil if there is no concrete type for this
}