testEncodes(base64().withSeparator("$", 4), "foobar", "Zm9v$YmFy");
    testEncodes(base32().withSeparator("*", 4), "foobar", "MZXW*6YTB*OI==*====");
  }

  public void testSeparatorSameAsPadChar() {
    assertThrows(IllegalArgumentException.class, () -> base64().withSeparator("=", 3));

    assertThrows(
        IllegalArgumentException.class, () -> base64().withPadChar('#').withSeparator("!#!", 3));
  }