@Test public void testDefaultMode() throws Exception {
		LexerGrammar g = new LexerGrammar(
			"lexer grammar L;\n"+
			"A : 'a' ;\n" +
			"X : 'x' ;\n" +
			"mode FOO;\n" +
			"B : 'b' ;\n" +
			"C : 'c' ;\n");
		String expecting =
			"s0->RuleStart_A_2\n" +
				"s0->RuleStart_X_4\n" +
				"RuleStart_A_2->s10\n" +
				"RuleStart_X_4->s12\n" +
				"s10-'a'->s11\n" +
				"s12-'x'->s13\n" +
				"s11->RuleStop_A_3\n" +
				"s13->RuleStop_X_5\n";
		checkTokensRule(g, "DEFAULT_MODE", expecting);
	}
Test for https://github.com/antlr/antlr4/issues/1369
 Repeated edges:

	 RuleStop_e_3->BlockEnd_26
	 RuleStop_e_3->BlockEnd_26
	 RuleStop_e_3->BlockEnd_26
@throws Exception
tool-testsuite/test/org/antlr/v4/test/tool/TestATNConstruction.java