public class CollectionRetainAllTester<E> extends AbstractCollectionTester<E> {

  /** A collection of elements to retain, along with a description for use in failure messages. */
  private class Target {
    private final Collection<E> toRetain;
    private final String description;

    private Target(Collection<E> toRetain, String description) {
      this.toRetain = toRetain;

        List<E> resultsForStrategy = new ArrayList<>();
        strategy.forEach(spliteratorSupplier.get(), resultsForStrategy::add);

        // TODO(cpovirk): better failure messages
        if ((characteristics & Spliterator.NONNULL) != 0) {
          assertFalse(resultsForStrategy.contains(null));
        }
        if ((characteristics & Spliterator.SORTED) != 0) {

  static final Integer NODE_NOT_IN_GRAPH = 1000;

  // TODO(user): Consider separating Strings that we've defined here to capture
  // identifiable substrings of expected error messages, from Strings that we've defined
  // here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.
  static final String ERROR_MODIFIABLE_SET = "Set returned is unexpectedly modifiable";

public class CollectionRetainAllTester<E> extends AbstractCollectionTester<E> {

  /** A collection of elements to retain, along with a description for use in failure messages. */
  private class Target {
    private final Collection<E> toRetain;
    private final String description;

    private Target(Collection<E> toRetain, String description) {
      this.toRetain = toRetain;

      initCause(conflictingStackTrace);
    }

    public ExampleStackTrace getConflictingStackTrace() {
      return conflictingStackTrace;
    }

    /**
     * Appends the chain of messages from the {@code conflictingStackTrace} to the original {@code
     * message}.
     */
    @Override
    public String getMessage() {
      // requireNonNull is safe because ExampleStackTrace sets a non-null message.

 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche
 */
// TODO: Descriptive assertion messages, with hints as to probable fixes.
// TODO: Add another constructor parameter indicating whether the class under test is ordered, and
// check the order if so.
// TODO: Refactor to share code with SetTestBuilder etc.

 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche
 */
// TODO: Descriptive assertion messages, with hints as to probable fixes.
// TODO: Add another constructor parameter indicating whether the class under test is ordered, and
// check the order if so.
// TODO: Refactor to share code with SetTestBuilder etc.

  static final String EDGE_NOT_IN_GRAPH = "edgeNotInGraph";

  // TODO(user): Consider separating Strings that we've defined here to capture
  // identifiable substrings of expected error messages, from Strings that we've defined
  // here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.
  static final String ERROR_PARALLEL_EDGE = "connected by a different edge";

  static final String EDGE_NOT_IN_GRAPH = "edgeNotInGraph";

  // TODO(user): Consider separating Strings that we've defined here to capture
  // identifiable substrings of expected error messages, from Strings that we've defined
  // here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.
  static final String ERROR_PARALLEL_EDGE = "connected by a different edge";

   * implementation. Using a reconstruction of the default Object.toString() prevents OOMs and stack
   * overflows, and helps avoid sensitive data inadvertently ending up in exception messages.
   */
  private void appendResultObject(StringBuilder builder, @CheckForNull Object o) {
    if (o == null) {
      builder.append("null");
    } else if (o == this) {
      builder.append("this future");