Antlr4Validator validator = PowerMock.createPartialMock(Antlr4Validator.class, "error");
expect(grammar.getType()).andReturn(GrammarType.LEXER);
expect(rule.eContainer()).andReturn(grammar);
expect(rule.eClass()).andReturn(eClass);
expect(rule.getName()).andReturn("rule");
expect(eClass.getEStructuralFeature("name")).andReturn(feature);
PowerMock.expectPrivate(validator, "error", "parser rule 'rule' not allowed in lexer",
rule, feature);