+ "(bar,1)=b, (bar,2)=null, (bar,3)=null, "
            + "(cat,1)=null, (cat,2)=null, (cat,3)=null]",
        table.cellSet().toString());
  }

  public void testRowKeySetToString_ordered() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals("[foo, bar, cat]", table.rowKeySet().toString());
  }

  public void testColumnKeySetToString_ordered() {

            + "(bar,1)=b, (bar,2)=null, (bar,3)=null, "
            + "(cat,1)=null, (cat,2)=null, (cat,3)=null]",
        table.cellSet().toString());
  }

  public void testRowKeySetToString_ordered() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals("[foo, bar, cat]", table.rowKeySet().toString());
  }

  public void testColumnKeySetToString_ordered() {

  public void testCopyOfSparse() {
    Table<Character, Integer, String> table = TreeBasedTable.create();
    table.put('x', 2, "foo");
    table.put('r', 1, "bar");
    table.put('c', 3, "baz");
    table.put('b', 7, "cat");
    table.put('e', 5, "dog");
    table.put('c', 0, "axe");
    table.put('e', 3, "tub");
    table.put('r', 4, "foo");
    table.put('x', 5, "bar");
    validateTableCopies(table);
  }

  }

  @GwtIncompatible // unreasonably slow
  public void testKeySetIteration() {
    new IteratorTester<String>(
        6,
        MODIFIABLE,
        newLinkedHashSet(asList("foo", "bar", "baz", "dog", "cat")),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      private @Nullable Multimap<String, Integer> multimap;

      @Override
      protected Iterator<String> newTargetIterator() {

  }

  @GwtIncompatible // unreasonably slow
  public void testKeySetIteration() {
    new IteratorTester<String>(
        6,
        MODIFIABLE,
        newLinkedHashSet(asList("foo", "bar", "baz", "dog", "cat")),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      private @Nullable Multimap<String, Integer> multimap;

      @Override
      protected Iterator<String> newTargetIterator() {
        multimap = create();

  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<String, Integer, String> table = HashBasedTable.create();
    table.put("foo", 1, "apple");
    table.put("bar", 1, "banana");
    table.put("foo", 3, "cat");
    return Tables.transformValues(table, TableCollectionTest.FIRST_CHARACTER).rowMap();
  }

          Maps.immutableEntry("bar", 1),
          Maps.immutableEntry("bar", 2),
          Maps.immutableEntry("foo", 3),
          Maps.immutableEntry("bar", 3),
          Maps.immutableEntry("cat", 2));
    }

    @Override
    public Collection<Entry<String, Integer>> create(Object... elements) {
      Multimap<String, Integer> multimap = createMultimap();
      for (Object element : elements) {

poor animal's feelings.  `I quite forgot you didn't like cats.'

  `Not like cats!' cried the Mouse, in a shrill, passionate
voice.  `Would YOU like cats if you were me?'

  `Well, perhaps not,' said Alice in a soothing tone:  `don't be
angry about it.  And yet I wish I could show you our cat Dinah:
I think you'd take a fancy to cats if you could only see her.

    } catch (NullPointerException expected) {
    }
    try {
      table.put("cat", null, cellValue('d'));
      fail();
    } catch (NullPointerException expected) {
    }
    if (supportsNullValues()) {
      assertNull(table.put("cat", 2, null));
      assertTrue(table.contains("cat", 2));
    } else {
      try {
        table.put("cat", 2, null);
        fail();
      } catch (NullPointerException expected) {
      }

    table.put("foo", 4, 'a');
    table.put("cat", 1, 'b');
    table.clear();
    populate(table, data);
    return table;
  }

  @Override
  protected TreeBasedTable<String, Integer, Character> create(@Nullable Object... data) {
    TreeBasedTable<String, Integer, Character> table = TreeBasedTable.create();
    table.put("foo", 4, 'a');
    table.put("cat", 1, 'b');
    table.clear();
    populate(table, data);