public void testsSetup()
{
_validator = new Validator();
_parser = new PostfixNotationParser();
_calculator = new Calculator(_validator, _parser);
_calculator
.AddOperation(new LeftBracket())
.AddOperation(new RightBracket())
.AddOperation(new PlusOperation())
.AddOperation(new MinusOperation())
.AddOperation(new MultiplyOperation());
_parser.SetOperationSigns(_calculator.GetOperations());
}