return new IsOdd();
  }

  /*
   * Tests for Predicates.alwaysTrue().
   */

  public void testAlwaysTrue_apply() {
    assertEvalsToTrue(Predicates.alwaysTrue());
  }

  public void testAlwaysTrue_equality() throws Exception {
    new EqualsTester()
        .addEqualityGroup(TRUE, Predicates.alwaysTrue())
        .addEqualityGroup(isOdd())
        .addEqualityGroup(Predicates.alwaysFalse())

    Function<Object, Boolean> alwaysTrue = Functions.forPredicate(Predicates.alwaysTrue());
    Function<Object, Boolean> alwaysFalse = Functions.forPredicate(Predicates.alwaysFalse());

    assertTrue(alwaysTrue.apply(0));
    assertFalse(alwaysFalse.apply(0));

    new EqualsTester()
        .addEqualityGroup(alwaysTrue, Functions.forPredicate(Predicates.alwaysTrue()))
        .addEqualityGroup(alwaysFalse)

    Function<Object, Boolean> alwaysTrue = Functions.forPredicate(Predicates.alwaysTrue());
    Function<Object, Boolean> alwaysFalse = Functions.forPredicate(Predicates.alwaysFalse());

    assertTrue(alwaysTrue.apply(0));
    assertFalse(alwaysFalse.apply(0));

    new EqualsTester()
        .addEqualityGroup(alwaysTrue, Functions.forPredicate(Predicates.alwaysTrue()))
        .addEqualityGroup(alwaysFalse)

  private enum ObjectPredicate implements Predicate<@Nullable Object> {
    /**
     * @see Predicates#alwaysTrue()
     */
    ALWAYS_TRUE {
      @Override
      public boolean apply(@Nullable Object o) {
        return true;
      }

      @Override
      public String toString() {
        return "Predicates.alwaysTrue()";
      }
    },
    /**
     * @see Predicates#alwaysFalse()
     */

    assertEquals(expected, actual);
  }

  public void testFilterMatchAll() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = filter(unfiltered, Predicates.alwaysTrue());
    List<String> expected = Lists.newArrayList("foo", "bar");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterNothing() {

    assertEquals("cool", find(list, Predicates.alwaysTrue(), "woot"));
    assertCanIterateAgain(list);
  }

  public void testTryFind() {
    Iterable<String> list = newArrayList("cool", "pants");
    assertThat(tryFind(list, equalTo("cool"))).hasValue("cool");
    assertThat(tryFind(list, equalTo("pants"))).hasValue("pants");
    assertThat(tryFind(list, Predicates.alwaysTrue())).hasValue("cool");

    assertEquals(expected, actual);
  }

  public void testFilterMatchAll() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = filter(unfiltered, Predicates.alwaysTrue());
    List<String> expected = Lists.newArrayList("foo", "bar");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterNothing() {

    assertEquals("cool", find(list, Predicates.alwaysTrue(), "woot"));
    assertCanIterateAgain(list);
  }

  public void testTryFind() {
    Iterable<String> list = newArrayList("cool", "pants");
    assertThat(tryFind(list, equalTo("cool"))).hasValue("cool");
    assertThat(tryFind(list, equalTo("pants"))).hasValue("pants");
    assertThat(tryFind(list, Predicates.alwaysTrue())).hasValue("cool");

          .put(Splitter.class, Splitter.on(','))
          .put(com.google.common.base.Optional.class, com.google.common.base.Optional.absent())
          .put(Predicate.class, Predicates.alwaysTrue())
          .put(Equivalence.class, Equivalence.equals())
          .put(Ticker.class, Ticker.systemTicker())
          .put(Stopwatch.class, Stopwatch.createUnstarted())
          // io types

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Predicates.alwaysTrue;
import static com.google.common.base.Predicates.equalTo;
import static com.google.common.base.Predicates.in;
import static com.google.common.base.Predicates.not;
import static com.google.common.collect.Iterators.emptyIterator;