Set<Character> positive = Sets.newHashSetWithExpectedSize(chars.length);
    for (char c : chars) {
      positive.add(c);
    }
    for (int c = 0; c <= Character.MAX_VALUE; c++) {
      assertFalse(positive.contains(Character.valueOf((char) c)) ^ m.matches((char) c));
    }
  }

  static char[] randomChars(Random rand, int size) {
    Set<Character> chars = new HashSet<>(size);

    public List<Character> create(Character[] elements) {
      char[] chars = Chars.toArray(Arrays.asList(elements));
      return Lists.charactersOf(String.copyValueOf(chars));
    }
  }

  public static class CharactersOfCharSequenceGenerator extends TestCharacterListGenerator {
    @Override
    public List<Character> create(Character[] elements) {
      char[] chars = Chars.toArray(Arrays.asList(elements));

  static long copyReaderToBuilder(Reader from, StringBuilder to) throws IOException {
    checkNotNull(from);
    checkNotNull(to);
    char[] buf = new char[DEFAULT_BUF_SIZE];
    int nRead;
    long total = 0;
    while ((nRead = from.read(buf)) != -1) {
      to.append(buf, 0, nRead);
      total += nRead;
    }
    return total;
  }

  /**

      actual += expected;
    }
    assertEquals(EXPECTED_FOUR_BYTE_ROUNDTRIPPABLE_COUNT, actual);
  }

  private static String newString(char... chars) {
    return new String(chars);
  }

  private static byte[] toByteArray(int... bytes) {
    byte[] realBytes = new byte[bytes.length];
    for (int i = 0; i < bytes.length; i++) {
      realBytes[i] = (byte) bytes[i];

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice
    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();
    Reader reader = concatenated.openStream(); // no need to worry about closing
    for (int i = 0; i < 8; i++) {
      builder.append((char) reader.read());
    }
    assertEquals(expected, builder.toString());

   *         .collect(
   *             flatteningToImmutableListMultimap(
   *                  str -> str.charAt(0),
   *                  str -> str.substring(1).chars().mapToObj(c -> (char) c));
   *
   * // is equivalent to
   *
   * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
   *     ImmutableListMultimap.<Character, Character>builder()

   *         .collect(
   *             flatteningToImmutableSetMultimap(
   *                  str -> str.charAt(0),
   *                  str -> str.substring(1).chars().mapToObj(c -> (char) c));
   *
   * // is equivalent to
   *
   * static final ImmutableSetMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
   *     ImmutableSetMultimap.<Character, Character>builder()

 * limitations under the License.
 */

package com.google.common.collect.testing;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.SampleElements.Chars;
import java.util.List;

/**
 * Generates {@code List<Character>} instances for test suites.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  public static void checkArgument(
      boolean expression, String errorMessageTemplate, char p1, char p2) {
    if (!expression) {
      throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
    }
  }

  /**

    StringBuilder builder = new StringBuilder("abc");
    List<Character> chars = Lists.charactersOf(builder);
    assertEquals(asList('a', 'b', 'c'), chars);
    builder.append("def");
    assertEquals(asList('a', 'b', 'c', 'd', 'e', 'f'), chars);
    builder.deleteCharAt(5);
    assertEquals(asList('a', 'b', 'c', 'd', 'e'), chars);
  }

  public void testNewArrayListEmpty() {