return 0; // Not called.
        }
      }
    }
  }

  /** Returns a new CharBuffer identical to buf, except twice the capacity. */
  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);
    Java8Compatibility.position(bigger, buf.position());
    Java8Compatibility.limit(bigger, buf.limit());

          return 0; // Not called.
        }
      }
    }
  }

  /** Returns a new CharBuffer identical to buf, except twice the capacity. */
  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);
    Java8Compatibility.position(bigger, buf.position());
    Java8Compatibility.limit(bigger, buf.limit());

    assertEquals(-1, empty.read());
  }

  public void testExhaust_readable() throws IOException {
    CharBuffer buf = CharBuffer.wrap(ASCII);
    assertEquals(ASCII.length(), CharStreams.exhaust(buf));
    assertEquals(0, buf.remaining());
    assertEquals(0, CharStreams.exhaust(buf));

    CharBuffer empty = CharBuffer.wrap("");
    assertEquals(0, CharStreams.exhaust(empty));
    assertEquals(0, empty.remaining());
  }

    assertEquals(-1, empty.read());
  }

  public void testExhaust_readable() throws IOException {
    CharBuffer buf = CharBuffer.wrap(ASCII);
    assertEquals(ASCII.length(), CharStreams.exhaust(buf));
    assertEquals(0, buf.remaining());
    assertEquals(0, CharStreams.exhaust(buf));

    CharBuffer empty = CharBuffer.wrap("");
    assertEquals(0, CharStreams.exhaust(empty));
    assertEquals(0, empty.remaining());
  }

  }

  @J2ktIncompatible // J2kt CharBuffer does not implement CharSequence so not recognized as empty
  @GwtIncompatible // CharBuffer not available
  public void testToStringOmitEmptyValues_charBuffer() {
    String toTest =
        MoreObjects.toStringHelper(new TestClass())
            .omitEmptyValues()
            .add("field1", "Hello")
            .add("field2", CharBuffer.allocate(0))
            .toString();

      File file = getFile();
      Reader reader = new InputStreamReader(new FileInputStream(file), UTF_8);
      StringBuilder builder = new StringBuilder();
      CharBuffer buffer = CharBuffer.allocate(100);
      while (reader.read(buffer) != -1) {
        Java8Compatibility.flip(buffer);
        builder.append(buffer);
        Java8Compatibility.clear(buffer);
      }

          .put(Reader.class, new StringReader(""))
          .put(StringReader.class, new StringReader(""))
          .put(Buffer.class, ByteBuffer.allocate(0))
          .put(CharBuffer.class, CharBuffer.allocate(0))
          .put(ByteBuffer.class, ByteBuffer.allocate(0))
          .put(ShortBuffer.class, ShortBuffer.allocate(0))
          .put(IntBuffer.class, IntBuffer.allocate(0))

import com.google.common.collect.Lists;
import java.io.BufferedReader;
import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.nio.CharBuffer;
import java.util.Arrays;
import java.util.List;

/**
 * Unit tests for {@link LineBuffer} and {@link LineReader}.
 *
 * @author Chris Nokleberg
 */
@AndroidIncompatible // occasionally very slow

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.io.IOException;
import java.io.Reader;
import java.nio.CharBuffer;
import javax.annotation.CheckForNull;

/**
 * A {@link Reader} that reads the characters in a {@link CharSequence}. Like {@code StringReader},
 * but works with any {@link CharSequence}.
 *
 * @author Colin Decker

import com.google.common.collect.Lists;
import java.io.BufferedReader;
import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.nio.CharBuffer;
import java.util.Arrays;
import java.util.List;

/**
 * Unit tests for {@link LineBuffer} and {@link LineReader}.
 *
 * @author Chris Nokleberg
 */
@AndroidIncompatible // occasionally very slow