@Test
public void testOpenTag() throws IOException {

    assertThat(of().open(DIV).writer.toString()).isEqualTo("<div>");
    assertThat(of().open(DIV, NO_CLASS).writer.toString()).isEqualTo("<div>");
    assertThat(of().open(DIV, HELLO_CLASS).writer.toString()).isEqualTo("<div class=\"hello\">");
}