/** Previous version of BigIntegerMath.factorial, kept for timing purposes. */
  private static BigInteger oldSlowFactorial(int n) {
    if (n <= 20) {
      return BigInteger.valueOf(LongMath.factorial(n));
    } else {
      int k = 20;
      return BigInteger.valueOf(LongMath.factorial(k)).multiply(oldSlowFactorial(k, n));
    }
  }

  /** Returns the product of {@code n1} exclusive through {@code n2} inclusive. */

    assertThat(filesystem.exists(cacheDir / "dir1")).isFalse()
  }

  private operator fun set(
    key: String,
    value0: String,
    value1: String,
  ) {
    val editor = cache.edit(key)!!
    editor.setString(0, value0)
    editor.setString(1, value1)
    editor.commit()
  }

  private fun assertAbsent(key: String) {
    val snapshot = cache[key]
    if (snapshot != null) {

        // Test negative values - should throw NullPointerException in private method via BigInteger.valueOf
        try {
            MemoryUtil.byteCountToDisplaySize(-1L);
            // If no exception, verify it handles negative as expected
        } catch (Exception e) {
            // Expected for negative values
        }

        // Test boundary values

  private static class IntHolder implements Serializable {
    private int value;

    IntHolder(int value) {
      this.value = value;
    }

    @Override
    public boolean equals(@Nullable Object o) {
      return (o instanceof IntHolder) && ((IntHolder) o).value == value;
    }

    @Override
    public int hashCode() {
      return value;
    }

      String str = String.valueOf(c);
      assertEquals(str, c, Ascii.toLowerCase(c));
      assertEquals(str, c, Ascii.toUpperCase(c));
      assertFalse(str, Ascii.isLowerCase(c));
      assertFalse(str, Ascii.isUpperCase(c));
    }
  }

  public void testCharsLower() {
    for (char c : LOWER.toCharArray()) {
      String str = String.valueOf(c);
      assertTrue(str, c == Ascii.toLowerCase(c));

      String str = String.valueOf(c);
      assertEquals(str, c, Ascii.toLowerCase(c));
      assertEquals(str, c, Ascii.toUpperCase(c));
      assertFalse(str, Ascii.isLowerCase(c));
      assertFalse(str, Ascii.isUpperCase(c));
    }
  }

  public void testCharsLower() {
    for (char c : LOWER.toCharArray()) {
      String str = String.valueOf(c);
      assertTrue(str, c == Ascii.toLowerCase(c));

        String result = StringUtil.join("-", "", null, "value", "", null);
        // First: "" (sb becomes "")
        // Second: sb.length() is 0, no delimiter, append null (sb becomes "null")
        // Third: sb.length() > 0, add "-" + "value" (sb becomes "null-value")
        // Fourth: sb.length() > 0, add "-" + "" (sb becomes "null-value-")
        // Fifth: sb.length() > 0, add "-" + null (sb becomes "null-value--null")

/**
 * @author higa
 *
 */
public class IntegerConversionUtilTest extends TestCase {

    /**
     * @throws Exception
     */
    public void testToInteger() throws Exception {
        assertEquals(Integer.valueOf("1000"), IntegerConversionUtil.toInteger("1,000"));
    }

    /**
     * @throws Exception
     */
    public void testToPrimitiveInt() throws Exception {

        // Verify return values
        assertEquals(FileInformation.FILE_ENDOFFILE_INFO, level);
        assertEquals(8, size);
        assertEquals(8, encoded);
        assertEquals(8, decoded);
        assertNotNull(str);
        assertTrue(str.contains("4096"));
    }

    /**
     * Test FileInformation constants match expected protocol values
     */
    @Test

        case java.util.Date d -> pattern != null ? Integer.valueOf(new SimpleDateFormat(pattern).format(d)) : (int) d.getTime();
        case Boolean b -> b ? 1 : 0;
        default -> toInteger(o.toString());
        };
    }

    private static Integer toInteger(final String s) {
        if (StringUtil.isEmpty(s)) {
            return null;
        }
        return Integer.valueOf(DecimalFormatUtil.normalize(s));
    }

    /**