assertEquals("foobar", Ascii.toLowerCase("fOobaR"));
  }

  public void testToUpperCase() {
    assertEquals(UPPER, Ascii.toUpperCase(LOWER));
    assertSame(UPPER, Ascii.toUpperCase(UPPER));
    assertEquals(IGNORED, Ascii.toUpperCase(IGNORED));
    assertEquals("FOOBAR", Ascii.toUpperCase("FoOBAr"));
  }

  public void testCharsIgnored() {
    for (char c : IGNORED.toCharArray()) {
      String str = String.valueOf(c);

    assertEquals("foobar", Ascii.toLowerCase("fOobaR"));
  }

  public void testToUpperCase() {
    assertEquals(UPPER, Ascii.toUpperCase(LOWER));
    assertSame(UPPER, Ascii.toUpperCase(UPPER));
    assertEquals(IGNORED, Ascii.toUpperCase(IGNORED));
    assertEquals("FOOBAR", Ascii.toUpperCase("FoOBAr"));
  }

  public void testCharsIgnored() {
    for (char c : IGNORED.toCharArray()) {
      String str = String.valueOf(c);

      for (Object o : elements) {
        @SuppressWarnings("unchecked")
        Entry<String, String> entry = (Entry<String, String>) o;
        multimap.put(entry.getKey(), Ascii.toUpperCase(entry.getValue()));
      }
      return transform(multimap);
    }

    abstract M transform(Multimap<String, String> multimap);

    @SuppressWarnings("unchecked")
    @Override

  public void testMap() {
    SpliteratorTester.of(
            () ->
                CollectSpliterators.map(
                    Arrays.spliterator(new String[] {"a", "b", "c", "d", "e"}), Ascii::toUpperCase))
        .expect("A", "B", "C", "D", "E");
  }

  public void testFlatMap() {
    SpliteratorTester.of(
            () ->
                CollectSpliterators.flatMap(

      }
      checkState(!hasUpperCase(), "Cannot call upperCase() on a mixed-case alphabet");
      char[] upperCased = new char[chars.length];
      for (int i = 0; i < chars.length; i++) {
        upperCased[i] = Ascii.toUpperCase(chars[i]);
      }
      Alphabet upperCase = new Alphabet(name + ".upperCase()", upperCased);
      return ignoreCase ? upperCase.ignoreCase() : upperCase;
    }

    Alphabet lowerCase() {

      for (Object o : elements) {
        @SuppressWarnings("unchecked")
        Entry<String, String> entry = (Entry<String, String>) o;
        multimap.put(entry.getKey(), Ascii.toUpperCase(entry.getValue()));
      }
      return transform(multimap);
    }

    abstract M transform(Multimap<String, String> multimap);

    @SuppressWarnings("unchecked")
    @Override