public function testFlattenTwoLevels() {
		$data = array(
			array(
				'Post' => array('id' => '1', 'author_id' => '1', 'title' => 'First Post'),
				'Author' => array('id' => '1', 'user' => 'nate', 'password' => 'foo')
			),
			array(
				'Post' => array(
					'id' => '2',
					'author_id' => '3',
					'title' => 'Second Post',
					'body' => 'Second Post Body'
				),
				'Author' => array('id' => '3', 'user' => 'joel', 'password' => null)
			)
		);

		$expected = array(
			'0.Post.id' => '1', '0.Post.author_id' => '1', '0.Post.title' => 'First Post',
			'0.Author.id' => '1', '0.Author.user' => 'nate', '0.Author.password' => 'foo',
			'1.Post.id' => '2', '1.Post.author_id' => '3', '1.Post.title' => 'Second Post',
			'1.Post.body' => 'Second Post Body', '1.Author.id' => '3',
			'1.Author.user' => 'joel', '1.Author.password' => null
		);
		$result = Set::flatten($data);
		$this->assertEqual($expected, $result);

		$result = Set::expand($result);
		$this->assertEqual($data, $result);

		$result = Set::flatten($data[0], array('separator' => '/'));
		$expected = array(
			'Post/id' => '1', 'Post/author_id' => '1', 'Post/title' => 'First Post',
			'Author/id' => '1', 'Author/user' => 'nate', 'Author/password' => 'foo'
		);
		$this->assertEqual($expected, $result);

		$result = Set::expand($expected, array('separator' => '/'));
		$this->assertEqual($data[0], $result);
	}