counter.write(data, 0, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    counter.write(data, 2, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    // Test that illegal arguments do not affect count

    counter.write(data, 0, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    counter.write(data, 2, 5);
    written += 5;
    assertEquals(written, out.size());
    assertEquals(written, counter.getCount());

    // Test that illegal arguments do not affect count

  }

  public void testOnlyOneOpen() throws Exception {
    final ByteSource source = newByteSource(0, 50);
    final int[] counter = new int[1];
    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }

  }

  public void testOnlyOneOpen() throws Exception {
    final ByteSource source = newByteSource(0, 50);
    final int[] counter = new int[1];
    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }

      void doIt(ImmutableLongArray.Builder builder, AtomicLong counter) {
        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {
      @Override
      void doIt(ImmutableLongArray.Builder builder, AtomicLong counter) {
        long[] array = new long[RANDOM.nextInt(10)];
        for (int i = 0; i < array.length; i++) {
          array[i] = counter.getAndIncrement();
        }
        builder.addAll(array);

      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {
      @Override
      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        double[] array = new double[RANDOM.nextInt(10)];
        for (int i = 0; i < array.length; i++) {
          array[i] = counter.getAndIncrement();
        }

  public void testSingleSimpleStats() {
    StatsCounter counter = new SimpleStatsCounter();
    for (int i = 0; i < 11; i++) {
      counter.recordHits(1);
    }
    for (int i = 0; i < 13; i++) {
      counter.recordLoadSuccess(i);
    }
    for (int i = 0; i < 17; i++) {
      counter.recordLoadException(i);
    }
    for (int i = 0; i < 23; i++) {
      counter.recordMisses(1);
    }

  /**
   * Returns a {@code new Object()} for every request, and increments a counter for every request.
   * The count is accessible via {@link #getCount}.
   */
  static class CountingLoader extends CacheLoader<Object, Object> {
    private final AtomicInteger count = new AtomicInteger();

    @Override
    public Object load(Object from) {
      count.incrementAndGet();
      return new Object();
    }

    for (int i = 0; i < SIZE; i++) {
      aa.set(i, (double) COUNTDOWN);
    }
    Counter c1 = new Counter(aa);
    Counter c2 = new Counter(aa);
    Thread t1 = newStartedThread(c1);
    Thread t2 = newStartedThread(c2);
    awaitTermination(t1);
    awaitTermination(t2);
    assertEquals(SIZE * COUNTDOWN, c1.counts + c2.counts);
  }

  /** a deserialized serialized array holds same values */

    assertEquals(-1, counter.read(new byte[30]));
    assertEquals(20, counter.getCount());
  }

  @SuppressWarnings("CheckReturnValue") // calling read() to skip a byte
  public void testMark() throws Exception {
    assertTrue(counter.markSupported());
    assertEquals(10, counter.read(new byte[10]));
    assertEquals(10, counter.getCount());
    counter.mark(5);
    counter.read();