*
   * @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

    assertFalse(CharSource.concat(c1, c2, c3).isEmpty());

    CharSource emptyConcat = CharSource.concat(CharSource.empty(), CharSource.empty());
    assertTrue(emptyConcat.isEmpty());
  }

  public void testConcat_infiniteIterable() throws IOException {
    CharSource source = CharSource.wrap("abcd");
    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

 * A generator of {@code TestSuite} instances for testing {@code CharSource} implementations.
 * 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).
public class CharSourceTester extends SourceSinkTester<CharSource, String, CharSourceFactory> {

        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

 * A generator of {@code TestSuite} instances for testing {@code CharSource} implementations.
 * 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).
public class CharSourceTester extends SourceSinkTester<CharSource, String, CharSourceFactory> {

        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

    @Override
    public String toString() {
      return "Resources.asByteSource(" + url + ")";
    }
  }

  /**
   * Returns a {@link CharSource} that reads from the given URL using the given character set.
   *
   * @since 14.0
   */
  public static CharSource asCharSource(URL url, Charset charset) {
    return asByteSource(url).asCharSource(charset);
  }

  /**
   * Reads all bytes from a URL into a byte array.

import java.io.InputStreamReader;
import java.io.Reader;

/**
 * A char source for testing that has configurable options.
 *
 * @author Colin Decker
 */
public class TestCharSource extends CharSource implements TestStreamSupplier {

  private final TestByteSource byteSource;

  public TestCharSource(String content, TestOption... options) {
    this.byteSource = new TestByteSource(content.getBytes(UTF_8), options);

import java.io.InputStreamReader;
import java.io.Reader;

/**
 * A char source for testing that has configurable options.
 *
 * @author Colin Decker
 */
public class TestCharSource extends CharSource implements TestStreamSupplier {

  private final TestByteSource byteSource;

  public TestCharSource(String content, TestOption... options) {
    this.byteSource = new TestByteSource(content.getBytes(UTF_8), options);

          .put(DoubleBuffer.class, DoubleBuffer.allocate(0))
          .put(File.class, new File(""))
          .put(ByteSource.class, ByteSource.empty())
          .put(CharSource.class, CharSource.empty())
          .put(ByteSink.class, NullByteSink.INSTANCE)
          .put(CharSink.class, NullByteSink.INSTANCE.asCharSink(UTF_8))
          // All collections are immutable empty. So safe for any type parameter.