@Test
public void shouldFindIndexOfSubstring() {

	Assert.assertEquals(2, new TextNode("abcdef").indexOf(new TextNode("cdef")));
	Assert.assertEquals(2, new TextNode("abcdef").indexOf(new TextNode("cde")));
	Assert.assertEquals(2, new TextNode("abcdef").indexOf(new TextNode("c")));
	Assert.assertEquals(0, new TextNode("abcdef").indexOf(new TextNode("ab")));
	Assert.assertEquals(0, new TextNode("abcdef").indexOf(new TextNode("")));
	Assert.assertEquals(5, new TextNode("abcdef").indexOf(new TextNode("f")));
}