private static File root() {
    return File.listRoots()[0];
  }

  /** Returns a {@code File} object for the given path parts. */
  private static File file(String first, String... more) {
    return file(new File(first), more);
  }

  /** Returns a {@code File} object for the given path parts. */
  private static File file(File first, String... more) {
    // not very efficient, but should definitely be correct

  private static File root() {
    return File.listRoots()[0];
  }

  /** Returns a {@code File} object for the given path parts. */
  private static File file(String first, String... more) {
    return file(new File(first), more);
  }

  /** Returns a {@code File} object for the given path parts. */
  private static File file(File first, String... more) {
    // not very efficient, but should definitely be correct

  public void testFromStringBadPort() {
    // Out-of-range ports.
    checkFromStringCase("google.com:65536", 1, null, 99, false);
    checkFromStringCase("google.com:9999999999", 1, null, 99, false);
    // Invalid port parts.
    checkFromStringCase("google.com:port", 1, null, 99, false);
    checkFromStringCase("google.com:-25", 1, null, 99, false);
    checkFromStringCase("google.com:+25", 1, null, 99, false);

    while (!descendant.equals(ancestor)) {
      classes.add(descendant);
      descendant = descendant.getSuperclass();
    }

    return classes;
  }

  /**
   * Not really a signature -- just the parts that affect whether one method is a fauxveride of a
   * method from an ancestor class.
   *
   * <p>See JLS 8.4.2 for the definition of the related "override-equivalent."
   */

    while (!descendant.equals(ancestor)) {
      classes.add(descendant);
      descendant = descendant.getSuperclass();
    }

    return classes;
  }

  /**
   * Not really a signature -- just the parts that affect whether one method is a fauxveride of a
   * method from an ancestor class.
   *
   * <p>See JLS 8.4.2 for the definition of the related "override-equivalent."
   */

    if (IPV4_DELIMITER_MATCHER.countIn(ipString) + 1 != IPV4_PART_COUNT) {
      return null; // Wrong number of parts
    }

    byte[] bytes = new byte[IPV4_PART_COUNT];
    int start = 0;
    // Iterate through the parts of the ip string.
    // Invariant: start is always the beginning of an octet.
    for (int i = 0; i < IPV4_PART_COUNT; i++) {

  public void testFromStringBadPort() {
    // Out-of-range ports.
    checkFromStringCase("google.com:65536", 1, null, 99, false);
    checkFromStringCase("google.com:9999999999", 1, null, 99, false);
    // Invalid port parts.
    checkFromStringCase("google.com:port", 1, null, 99, false);
    checkFromStringCase("google.com:-25", 1, null, 99, false);
    checkFromStringCase("google.com:+25", 1, null, 99, false);

    return stringWriter.toString();
  }

  /**
   * Returns the stack trace of {@code throwable}, possibly providing slower iteration over the full
   * trace but faster iteration over parts of the trace. Here, "slower" and "faster" are defined in
   * comparison to the normal way to access the stack trace, {@link Throwable#getStackTrace()

    return stringWriter.toString();
  }

  /**
   * Returns the stack trace of {@code throwable}, possibly providing slower iteration over the full
   * trace but faster iteration over parts of the trace. Here, "slower" and "faster" are defined in
   * comparison to the normal way to access the stack trace, {@link Throwable#getStackTrace()

    public OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> getInnerGenerator() {
      return mapGenerator;
    }
  }

  // TODO: investigate some API changes to SampleElements that would tidy up
  // parts of the following classes.

  static <K extends @Nullable Object, V extends @Nullable Object>
      TestSetGenerator<K> keySetGenerator(
          OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {