public void AddsYearlyTaxCorrectly_ForDifferentCities() { _sut.AddYearlyTax("a", 2016, 0.1m); _sut.AddYearlyTax("b", 2016, 0.7m); var result = _sut.GetTax("a", DateTime.Parse("2016.02.02")); Assert.That(result, Is.EqualTo(0.1m)); result = _sut.GetTax("b", DateTime.Parse("2016.12.02")); Assert.That(result, Is.EqualTo(0.7m)); }