val nameprep = reader.readNameprep("/okhttp3/internal/idn".toPath())
    assertThat((nameprep.unassigned as RangeListCodePointSet).ranges).hasSize(396)
    assertThat((nameprep.mapping as MappingListCodePointMapping).mappings).hasSize(1398)
    assertThat((nameprep.prohibitSet as RangeListCodePointSet).ranges).hasSize(78)
    assertThat((nameprep.randalcatSet as RangeListCodePointSet).ranges).hasSize(34)

IDN Data
========

In order to implement Nameprep (RFC 3491), OkHttp uses Unicode tables specified in Stringprep
(RFC 3454). Fragments of this RFC are dumped into the files in this directory and parsed by
`StringprepTablesReader` into a model that can be used at runtime.

This format is chosen to make it easy to validate that these tables are consistent with the RFC.

```
cd okhttp/src/test/resources/okhttp3/internal/idn/

 * limitations under the License.
 */
package okhttp3.internal.idn

import okio.Buffer
import okio.BufferedSource

/**
 * An implementation of Stringprep ([RFC 3454]) intended for use with Nameprep ([RFC 3491]).
 *
 * [RFC 3454]: https://datatracker.ietf.org/doc/html/rfc3454
 * [RFC 3491]: https://datatracker.ietf.org/doc/html/rfc3491
 */
class Stringprep(
  /** Unassigned code points. */

import okio.Options
import okio.Path
import okio.buffer
import okio.use

class StringprepTablesReader(
  private val fileSystem: FileSystem,
) {
  /**
   * Returns a [Stringprep] that uses the tables of Nameprep ([RFC 3491]).
   *
   * [RFC 3491]: https://datatracker.ietf.org/doc/html/rfc3491
   */
  fun readNameprep(base: Path): Stringprep {
    val unassigned = readCodePointSet(base / "rfc3454.A.1.txt")
    val mapping =