* signatures.
 *
 * @param codePointLimit the number of code points to read in order to make a decision.
 */
internal fun BufferedSource.isProbablyUtf8(codePointLimit: Long = Long.MAX_VALUE): Boolean {
  try {
    val peek = peek()
    for (i in 0 until codePointLimit) {
      if (peek.exhausted()) {
        break
      }

class IsProbablyUtf8Test {
  @Test fun isProbablyUtf8() {
    assertThat(Buffer().isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeUtf8("abc").isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeUtf8("new\r\nlines").isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeUtf8("white\t space").isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeUtf8("Слава Україні!").isProbablyUtf8(16L)).isTrue()