assertThat(TEN.pow(result)).isAtMost(x);
        assertThat(TEN.pow(result + 1)).isGreaterThan(x);
      }
    }
  }

  @GwtIncompatible // TODO
  public void testLog10Ceiling() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      for (RoundingMode mode : asList(CEILING, UP)) {
        int result = BigIntegerMath.log10(x, mode);
        assertThat(TEN.pow(result)).isAtLeast(x);