@Test
public void testGetRootRuleExternal() throws Exception {

    final InputStream in =
        TestGrammar.class.getResourceAsStream("test.grxml");
    final InputSource source = new InputSource(in);
    SrgsXmlDocument document = new SrgsXmlDocument(source);
    Grammar grammar = document.getGrammar();
    Rule rootRule = grammar.getRootRule();
    Assert.assertNotNull(rootRule);
    Assert.assertEquals("main", rootRule.getId());
}