public void EvaluateTests(string expression, int expectedResult)
{
var letExpression = new LetExpression();
int result = letExpression.Evaluate(expression);
Assert.That(result, Is.EqualTo(expectedResult));
}
public void ErrorEvaluateTests(string expression)
{
var letExpression = new LetExpression();
Assert.Throws(typeof(ArithmeticException), () => letExpression.Evaluate(expression));
}