public void ShoudNotReturnNextValue()
{
RangeValueProvider provider;
provider = new RangeValueProvider();
Assert.ThrowsException <ArgumentOutOfRangeException>(() => provider.GetNextValue(char.MaxValue));
}
public void ShoudReturnNextValue()
{
RangeValueProvider provider;
provider = new RangeValueProvider();
Assert.AreEqual('b', provider.GetNextValue('a'));
}