assertThat(stringPrep("localhost")).isEqualTo("localhost")
    assertThat(stringPrep("Localhost")).isEqualTo("localhost")
    assertThat(stringPrep("LOCALHOST")).isEqualTo("localhost")
    assertThat(stringPrep("abc123def")).isEqualTo("abc123def")
    assertThat(stringPrep("ß")).isEqualTo("ss")
    assertThat(stringPrep("İ")).isEqualTo("i̇")
    assertThat(stringPrep("ϒ")).isEqualTo("υ")
    assertThat(stringPrep("ὒ")).isEqualTo("ὒ")
  }

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 =
      MappingListCodePointMapping(

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/

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. */
  val unassigned: CodePointSet,

github.com/xdg/scram v1.0.5 h1:TuS0RFmt5Is5qm9Tm2SoD89OPqe4IRiFtyFY4iwWXsw=
github.com/xdg/scram v1.0.5/go.mod h1:lB8K/P019DLNhemzwFU4jHLhdvlE6uDZjXFejJXr49I=
github.com/xdg/stringprep v1.0.3 h1:cmL5Enob4W83ti/ZHuZLuKD/xqJfus4fVPwE+/BDm+4=
github.com/xdg/stringprep v1.0.3/go.mod h1:Jhud4/sHMO4oL310DaZAKk9ZaJ08SJfe+sJh0HrGL1Y=
github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:aYKd//L2LvnjZzWKhF00oedf4jCCReLcmhLdhm1A27Q=

      of your accepting any such warranty or additional liability.

================================================================

github.com/xdg/stringprep
https://github.com/xdg/stringprep
----------------------------------------------------------------

                                 Apache License
                           Version 2.0, January 2004