anchor.diff:    }
   
     void test_stringLength_int() {
  -    try {
  +    expect(() {
         _assertStringLength(_intValue(null), _intValue(0));
  -      fail("Expected EvaluationException");
  -    } on EvaluationException {}
  +    }, throwsEvaluationException);
     }
   
     void test_stringLength_knownString() {
  
positive.code:   void _assertTimes(
        DartObjectImpl expected, DartObjectImpl left, DartObjectImpl right) {
      if (expected == null) {
        try {
          left.times(_typeProvider, right);
          fail("Expected an EvaluationException");
        } on EvaluationException {}
      } else {
        DartObjectImpl result = left.times(_typeProvider, right);
        expect(result, isNotNull);
  
negative.code:   void _assertShiftRight(
        DartObjectImpl expected, DartObjectImpl left, DartObjectImpl right) {
      if (expected == null) {
        expect(() {
          left.shiftRight(_typeProvider, right);
        }, throwsEvaluationException);
      } else {
        DartObjectImpl result = left.shiftRight(_typeProvider, right);
        expect(result, isNotNull);
  