public void ShouldPassAllNumbers()
{
Assert.IsTrue(_inputValidator.IsValidForCalculations('0'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('1'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('2'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('3'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('4'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('5'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('6'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('7'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('8'));
Assert.IsTrue(_inputValidator.IsValidForCalculations('9'));
}