testInsertsWithDefaultComparator() {
    const tree = new AvlTree();
    const values = ['bill', 'blake', 'elliot', 'jacob', 'john', 'myles', 'ted'];

    // Insert strings into tree out of order
    tree.add(values[4]);
    tree.add(values[3]);
    tree.add(values[0]);
    tree.add(values[6]);
    tree.add(values[5]);
    tree.add(values[1]);
    tree.add(values[2]);

    // Verify strings are stored in sorted order
    let i = 0;
    tree.inOrderTraverse((value) => {
      assertEquals(values[i], value);
      i += 1;
    });
    assertEquals(i, values.length);

    // Verify that no nodes are visited if the start value is larger than all
    // values
    tree.inOrderTraverse(/**
                            @suppress {checkTypes} suppression added to enable
                            type checking
                          */
                         (value) => {
                           fail();
                         },
                         'zed');

    // Verify strings are stored in sorted order
    i = values.length;
    tree.reverseOrderTraverse((value) => {
      i--;
      assertEquals(values[i], value);
    });
    assertEquals(i, 0);

    // Verify that no nodes are visited if the start value is smaller than all
    // values
    tree.reverseOrderTraverse(/**
                                 @suppress {checkTypes} suppression added to
                                 enable type checking
                               */
                              (value) => {
                                fail();
                              },
                              'aardvark');
  }
This test verifies that we can insert strings into the AvlTree and have
them be stored and sorted correctly by the default comparator.