import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Set;

/**
 * Optional features of classes derived from {@code Set}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum SetFeature implements Feature<Set> {
  GENERAL_PURPOSE(CollectionFeature.GENERAL_PURPOSE);

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.List;
import java.util.Set;

/**
 * Optional features of classes derived from {@code List}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum ListFeature implements Feature<List> {
  SUPPORTS_SET,

import java.util.Set;

/**
 * Base class for enumerating the features of an interface to be tested.
 *
 * @param <T> The interface whose features are to be enumerated.
 * @author George van den Driessche
 */
@GwtCompatible
public interface Feature<T> {
  /** Returns the set of features that are implied by this feature. */
  Set<Feature<? super T>> getImpliedFeatures();

import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;

/**
 * Implementation helper for {@link TestMapGenerator} for use with maps of strings.
 *
 * @author Chris Povirk
 * @author Jared Levy
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked
public abstract class TestStringMapGenerator implements TestMapGenerator<String, String> {

  @Override
  public SampleElements<Entry<String, String>> samples() {

import com.google.common.annotations.J2ktIncompatible;
import java.util.Set;

/**
 * Thrown when requirements on a tester method or class conflict with each other.
 *
 * @author George van den Driessche
 */
@GwtCompatible
public class ConflictingRequirementsException extends Exception {
  private final Set<Feature<?>> conflicts;
  private final Object source;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import java.util.Set;
import org.junit.Ignore;

/**
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

 *
 * <p>This is needed because annotations can't implement interfaces, which is also why reflection is
 * used to extract values from the properties of the various annotations.
 *
 * @author George van den Driessche
 */
@Target(value = {ElementType.ANNOTATION_TYPE})
@Retention(value = RetentionPolicy.RUNTIME)
@Documented
@GwtCompatible

import org.jspecify.annotations.Nullable;

/**
 * To be implemented by test generators that can produce test subjects without requiring any
 * parameters.
 *
 * @param <T> the type created by this generator.
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked
public interface TestSubjectGenerator<T extends @Nullable Object> {
  T createTestSubject();

 * both {@link Collection} and {@link Map}; since there isn't an established collective noun that
 * encompasses both of these, 'container' is used.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked
public interface TestContainerGenerator<T, E extends @Nullable Object> {
  /** Returns the sample elements that this generate populates its container with. */

import java.util.Arrays;
import java.util.Collection;
import java.util.List;

/**
 * Abstract superclass of all test-suite builders for collection interfaces.
 *
 * @author George van den Driessche
 */
@GwtIncompatible
public abstract class AbstractCollectionTestSuiteBuilder<
        B extends AbstractCollectionTestSuiteBuilder<B, E>, E>