public void testIsWrapperType() {
    assertThat(Primitives.isWrapperType(Void.class)).isTrue();
    assertThat(Primitives.isWrapperType(void.class)).isFalse();
  }

  public void testWrap() {
    assertThat(Primitives.wrap(int.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(Integer.class)).isSameInstanceAs(Integer.class);

  public void testIsWrapperType() {
    assertThat(Primitives.isWrapperType(Void.class)).isTrue();
    assertThat(Primitives.isWrapperType(void.class)).isFalse();
  }

  public void testWrap() {
    assertThat(Primitives.wrap(int.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(Integer.class)).isSameInstanceAs(Integer.class);

import junit.framework.TestCase;

/** Tests for {@code CollectSpliterators}. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class CollectSpliteratorsTest extends TestCase {
  public void testMap() {
    SpliteratorTester.of(
            () ->
                CollectSpliterators.map(
                    Arrays.spliterator(new String[] {"a", "b", "c", "d", "e"}), Ascii::toUpperCase))

  }

  public void test_useForNull_twice() {
    Joiner j = Joiner.on("x").useForNull("y");
    assertThrows(UnsupportedOperationException.class, () -> j.useForNull("y"));
  }

  public void testMap() {
    MapJoiner j = Joiner.on(';').withKeyValueSeparator(':');
    assertEquals("", j.join(ImmutableMap.of()));
    assertEquals(":", j.join(ImmutableMap.of("", "")));