anchor.diff:    print(a.test);
   }
   ''');
  +  }
  +
  +  test_exchangeBinaryExpressionArguments_BAD_extraLength() async {
  +    resolveTestUnit('''
  +main() {
  +  111 + 222;
  +}
  +''');
  +    length = 3;
  +    await assertNoAssistAt('+ 222', DartAssistKind.EXCHANGE_OPERANDS);
  +  }
  +
  +  test_exchangeBinaryExpressionArguments_BAD_onOperand() async {
  +    resolveTestUnit('''
  +main() {
  +  111 + 222;
  +}
  +''');
  +    length = 3;
  +    await assertNoAssistAt('11 +', DartAssistKind.EXCHANGE_OPERANDS);
  +  }
  +
  +  test_exchangeBinaryExpressionArguments_BAD_selectionWithBinary() async {
  +    resolveTestUnit('''
  +main() {
  +  1 + 2 + 3;
  +}
  +''');
  +    length = '1 + 2 + 3'.length;
  +    await assertNoAssistAt('1 + 2 + 3', DartAssistKind.EXCHANGE_OPERANDS);
     }
   
     test_exchangeBinaryExpressionArguments_OK_compare() async {
  
positive.code: }
  ''');
      await assertHasAssistAt(
          'v;',
          DartAssistKind.JOIN_VARIABLE_DECLARATION,
          '''
  
negative.code:         'v; // marker', DartAssistKind.JOIN_VARIABLE_DECLARATION);
    }
  
    test_joinVariableDeclaration_onAssignment_BAD_notOneVariable() async {
      resolveTestUnit('''
  main() {
    var v, v2;
  