public void Predecessor_ValidInput_ReturnsCorrectPostalCode(string postalCode, string postalCodePredecessor) { var code = new RUPostalCode(postalCode); var codePredecessor = new RUPostalCode(postalCodePredecessor); Assert.AreEqual(codePredecessor, code.Predecessor); Assert.AreEqual(codePredecessor.ToString(), code.Predecessor.ToString()); Assert.AreEqual(codePredecessor.ToHumanReadableString(), code.Predecessor.ToHumanReadableString()); }