}

  public void testConcat() {
    assertThat(Doubles.concat()).isEqualTo(EMPTY);
    assertThat(Doubles.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Doubles.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Doubles.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Doubles.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Doubles.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);

    assertThat(Chars.concat()).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Chars.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1, ARRAY1, ARRAY1))

  public void testConcat() {
    assertThat(Booleans.concat()).isEqualTo(EMPTY);
    assertThat(Booleans.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Booleans.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Booleans.concat(ARRAY_FALSE)).isEqualTo(ARRAY_FALSE);
    assertThat(Booleans.concat(ARRAY_FALSE)).isNotSameInstanceAs(ARRAY_FALSE);
    assertThat(Booleans.concat(EMPTY, ARRAY_FALSE, EMPTY)).isEqualTo(ARRAY_FALSE);

   * iterator supports it.
   *
   * <p><b>Java 8+ users:</b> The {@code Stream} equivalent of this method is {@code
   * Stream.concat(a, b)}.
   */
  public static <T extends @Nullable Object> Iterable<T> concat(
      Iterable<? extends T> a, Iterable<? extends T> b) {
    return FluentIterable.concat(a, b);
  }

  /**
   * Combines three iterables into a single iterable. The returned iterable has an iterator that

    out.write(chunk1);
    assertThat(out.getFile()).isNull();

    out.write(chunk2);
    assertThat(out.getFile()).isNotNull();
    assertThat(source.read()).isEqualTo(concat(chunk1, chunk2));

    out.write(chunk3);
    assertThat(source.read()).isEqualTo(concat(chunk1, chunk2, chunk3));

    out.reset();
  }

  }

  public void testConcat() {
    assertThat(Shorts.concat()).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Shorts.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Shorts.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);

    assertThat(Ints.concat()).isEqualTo(EMPTY);
    assertThat(Ints.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Ints.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Ints.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Ints.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1, ARRAY1, ARRAY1))

    out.write(chunk1);
    assertThat(out.getFile()).isNull();

    out.write(chunk2);
    assertThat(out.getFile()).isNotNull();
    assertThat(source.read()).isEqualTo(concat(chunk1, chunk2));

    out.write(chunk3);
    assertThat(source.read()).isEqualTo(concat(chunk1, chunk2, chunk3));

    out.reset();
  }

    assertEquals("d", itr2.next());
    assertEquals("c", itr2.next());
  }

  public void testConcatPartiallyAdvancedFirst() {
    Iterator<String> itr1 = Iterators.concat(singletonIterator("a"), Iterators.forArray("b", "c"));
    assertEquals("a", itr1.next());
    assertEquals("b", itr1.next());
    Iterator<String> itr2 = Iterators.concat(itr1, singletonIterator("d"));

  interface Y {}

  static class A implements X, Y {}

  static class B implements X, Y {}

  /**
   * This test passes if the {@code concat(…).filter(…).filter(…)} statement at the end compiles.
   * That statement compiles only if {@link FluentIterable#concat concat(aIterable, bIterable)}
   * returns a {@link FluentIterable} of elements of an anonymous type whose supertypes are the <a