public void testMemoizeNonSerializable() throws Exception {
    CountingSupplier countingSupplier = new CountingSupplier();
    Supplier<Integer> memoizedSupplier = Suppliers.memoize(countingSupplier);
    assertThat(memoizedSupplier.toString()).isEqualTo("Suppliers.memoize(CountingSupplier)");
    checkMemoize(countingSupplier, memoizedSupplier);
    // Calls to the original memoized supplier shouldn't affect its copy.

  public void testMemoizeNonSerializable() throws Exception {
    CountingSupplier countingSupplier = new CountingSupplier();
    Supplier<Integer> memoizedSupplier = Suppliers.memoize(countingSupplier);
    assertThat(memoizedSupplier.toString()).isEqualTo("Suppliers.memoize(CountingSupplier)");
    checkMemoize(countingSupplier, memoizedSupplier);
    // Calls to the original memoized supplier shouldn't affect its copy.

    RED,
    YELLOW,
    GREEN
  }

  private abstract static class CountingSupplier<E> implements Supplier<E>, Serializable {
    int count;

    abstract E getImpl();

    @Override
    public E get() {
      count++;
      return getImpl();
    }
  }

  private static class QueueSupplier extends CountingSupplier<Queue<Integer>> {
    @Override
    public Queue<Integer> getImpl() {