*
   * @param sources the sources to concatenate
   * @return a {@code CharSource} containing the concatenated data
   * @since 15.0
   */
  public static CharSource concat(Iterable<? extends CharSource> sources) {
    return new ConcatenatedCharSource(sources);
  }

  /**
   * Concatenates multiple {@link CharSource} instances into a single source. Streams returned from

    String testString = "abcdefgh";
    CharSource source = newCharSource(testString);
    Reader joinedReader = CharSource.concat(source, source).openStream();

    String expectedString = testString + testString;
    assertThat(CharStreams.toString(joinedReader)).isEqualTo(expectedString);
  }

  private static CharSource newCharSource(String text) {
    return new CharSource() {
      @Override
      public Reader openStream() {

    CharSource c1 = CharSource.wrap("abc");
    CharSource c2 = CharSource.wrap("");
    CharSource c3 = CharSource.wrap("de");

    String expected = "abcde";

    assertThat(CharSource.concat(ImmutableList.of(c1, c2, c3)).read()).isEqualTo(expected);
    assertThat(CharSource.concat(c1, c2, c3).read()).isEqualTo(expected);

 * Generates tests of all methods on a {@code CharSource} given various inputs the source is
 * expected to contain.
 *
 * @author Colin Decker
 */
@AndroidIncompatible // TODO(b/230620681): Make this available (even though we won't run it).
@NullUnmarked
public class CharSourceTester extends SourceSinkTester<CharSource, String, CharSourceFactory> {

 *
 * @author Bin Zhu
 * @since 1.0
 */
@J2ktIncompatible
@GwtIncompatible
final class MultiReader extends Reader {
  private final Iterator<? extends CharSource> it;
  private @Nullable Reader current;

  MultiReader(Iterator<? extends CharSource> readers) throws IOException {
    this.it = readers;
    advance();
  }

  /** Closes the current reader and opens the next one, if any. */

        factory.tearDown();
      }
    };
  }

  private static class StringSourceFactory implements CharSourceFactory {

    @Override
    public CharSource createSource(String data) throws IOException {
      return CharSource.wrap(data);
    }

    @Override
    public String getExpected(String data) {
      return data;
    }

    @Override

public abstract class ByteSource {

  /** Constructor for use by subclasses. */
  protected ByteSource() {}

  /**
   * Returns a {@link CharSource} view of this byte source that decodes bytes read from this source
   * as characters using the given {@link Charset}.
   *
   * <p>If {@link CharSource#asByteSource} is called on the returned source with the same charset,

 * Generates tests of all methods on a {@code ByteSource} given various inputs the source is
 * expected to contain as well as sub-suites for testing the {@code CharSource} view and {@code
 * slice()} views in the same way.
 *
 * @author Colin Decker
 */
@AndroidIncompatible // TODO(b/230620681): Make this available (even though we won't run it).
@NullUnmarked

    }

    /**
     * Returns a {@link CharSource} view of the resource from which its bytes can be read as
     * characters decoded with the given {@code charset}.
     *
     * @throws NoSuchElementException if the resource cannot be loaded through the class loader,
     *     despite physically existing in the class path.
     * @since 20.0
     */
    public final CharSource asCharSource(Charset charset) {

 * Generates tests of all methods on a {@code ByteSource} given various inputs the source is
 * expected to contain as well as sub-suites for testing the {@code CharSource} view and {@code
 * slice()} views in the same way.
 *
 * @author Colin Decker
 */
@AndroidIncompatible // TODO(b/230620681): Make this available (even though we won't run it).
@NullUnmarked