navigableSet = (NavigableSet<E>) getSet();
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testEmptySetPollFirst() {
    assertNull(navigableSet.pollFirst());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptySetNearby() {
    assertNull(navigableSet.lower(e0()));
    assertNull(navigableSet.floor(e0()));

            assertEquals(testStringTrue.charAt(i), (char) unicodeStringTrue.buffer[i], "Character mismatch");
        }
        assertEquals(0, unicodeStringTrue.buffer[testStringTrue.length()], "Last character should be zero");

        // Test with a non-empty string and zterm = false
        String testStringFalse = "Hello";
        UnicodeString unicodeStringFalse = new UnicodeString(testStringFalse, false);

    in.put(Number.class, 0);
    in.put(Double.class, Math.PI);
    ClassToInstanceMap<Number> map = ImmutableClassToInstanceMap.copyOf(in);
    assertEquals(2, map.size());

    Number zero = map.getInstance(Number.class);
    assertEquals(0, zero);

    Double pi = map.getInstance(Double.class);
    assertThat(pi).isEqualTo(Math.PI);

    assertThat(ImmutableClassToInstanceMap.copyOf(map)).isSameInstanceAs(map);
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAdd_supportedPresent() {
    assertFalse("add(present) should return false", getSet().add(e0()));
    expectUnchanged();
  }

  @CollectionFeature.Require(value = {SUPPORTS_ADD, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testAdd_supportedNullPresent() {
    E[] array = createArrayWithNullElement();

import static com.google.common.collect.testing.Helpers.copyToList;
import static com.google.common.collect.testing.Helpers.copyToSet;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_PUT;

import com.google.common.annotations.GwtCompatible;

                    return union(emptySet(), emptySet());
                  }
                })
            .named("empty U empty")
            .withFeatures(CollectionSize.ZERO, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(
                new TestStringSetGenerator() {
                  @Override

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ADD;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.testers.ReflectionFreeAssertThrows.assertThrows;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ADD;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.testers.ReflectionFreeAssertThrows.assertThrows;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import static com.google.common.collect.testing.Helpers.assertContentsAnyOrder;
import static com.google.common.collect.testing.Helpers.copyToList;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;

import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.features.CollectionFeature;