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Who cares about Domain Rules?

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20 Nov 2006MIT12 min read 95.7K   85   118  
With this article, I am evolving a domain problem towards the best possible solution.
 
using NUnit.Framework;

namespace BusinessRules.Evolution_One.Tests
{
    [TestFixture]
    public class InvestorFixture
    {
        [Test]
        public void TaxRateCalculatedCorrectlyForUS()
        {
            // Create the instance of the investor
            IInvestor investor = new UsaInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.10, investor.TaxRate);
            investor.Income = 1500.00;
            Assert.AreEqual(0.10, investor.TaxRate);
            investor.Income = 7550.99;
            Assert.AreEqual(0.10, investor.TaxRate);

            investor.Income = 7551.00;
            Assert.AreEqual(0.15, investor.TaxRate);
            investor.Income = 28000.00;
            Assert.AreEqual(0.15, investor.TaxRate);
            investor.Income = 30650.99;
            Assert.AreEqual(0.15, investor.TaxRate);

            investor.Income = 30651.00;
            Assert.AreEqual(0.25, investor.TaxRate);
            investor.Income = 65000.00;
            Assert.AreEqual(0.25, investor.TaxRate);
            investor.Income = 74200.99;
            Assert.AreEqual(0.25, investor.TaxRate);

            investor.Income = 74201.00;
            Assert.AreEqual(0.28, investor.TaxRate);
            investor.Income = 84526.00;
            Assert.AreEqual(0.28, investor.TaxRate);
            investor.Income = 154800.99;
            Assert.AreEqual(0.28, investor.TaxRate);

            investor.Income = 154801.00;
            Assert.AreEqual(0.33, investor.TaxRate);
            investor.Income = 205456.44;
            Assert.AreEqual(0.33, investor.TaxRate);
            investor.Income = 336550.99;
            Assert.AreEqual(0.33, investor.TaxRate);

            investor.Income = 336551.00;
            Assert.AreEqual(0.35, investor.TaxRate);
            investor.Income = 536551.00;
            Assert.AreEqual(0.35, investor.TaxRate);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(0.35, investor.TaxRate);
        }

        [Test]
        public void TaxLiabilityCalculatedCorrectlyForUS()
        {
            // Create the instance of the investor
            IInvestor investor = new UsaInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 1500.00;
            Assert.AreEqual(150.00, investor.TaxLiability, 2.0);
            investor.Income = 7550.99;
            Assert.AreEqual(755.10, investor.TaxLiability, 2.0);

            investor.Income = 7551.00;
            Assert.AreEqual(755.10, investor.TaxLiability, 2.0);
            investor.Income = 28000.00;
            Assert.AreEqual(3822.45, investor.TaxLiability, 2.0);
            investor.Income = 30650.99;
            Assert.AreEqual(4220.10, investor.TaxLiability, 2.0);

            investor.Income = 30651.00;
            Assert.AreEqual(4220.10, investor.TaxLiability, 2.0);
            investor.Income = 65000.00;
            Assert.AreEqual(12807.35, investor.TaxLiability, 2.0);
            investor.Income = 74200.99;
            Assert.AreEqual(15107.60, investor.TaxLiability, 2.0);

            investor.Income = 74201.00;
            Assert.AreEqual(15107.60, investor.TaxLiability, 2.0);
            investor.Income = 84526.00;
            Assert.AreEqual(17998.60, investor.TaxLiability, 2.0);
            investor.Income = 154800.99;
            Assert.AreEqual(37675.60, investor.TaxLiability, 2.0);

            investor.Income = 154801.00;
            Assert.AreEqual(37675.60, investor.TaxLiability, 2.0);
            investor.Income = 205456.44;
            Assert.AreEqual(54391.89, investor.TaxLiability, 2.0);
            investor.Income = 336550.99;
            Assert.AreEqual(97653.09, investor.TaxLiability, 2.0);

            investor.Income = 336551.00;
            Assert.AreEqual(97653.09, investor.TaxLiability, 2.0);
            investor.Income = 536551.00;
            Assert.AreEqual(167653.09, investor.TaxLiability, 2.0);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(6.2919259720181043E+307, investor.TaxLiability, 2.0);
        }

        [Test]
        public void TaxRateCalculatedCorrectlyForAustralia()
        {
            // Create the instance of the investor
            IInvestor investor = new AustralianInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 1500.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 6000.99;
            Assert.AreEqual(0.0, investor.TaxRate);

            investor.Income = 6001.00;
            Assert.AreEqual(0.15, investor.TaxRate);
            investor.Income = 22258.32;
            Assert.AreEqual(0.15, investor.TaxRate);
            investor.Income = 25000.99;
            Assert.AreEqual(0.15, investor.TaxRate);

            investor.Income = 25001.00;
            Assert.AreEqual(0.30, investor.TaxRate);
            investor.Income = 65000.00;
            Assert.AreEqual(0.30, investor.TaxRate);
            investor.Income = 75000.99;
            Assert.AreEqual(0.30, investor.TaxRate);

            investor.Income = 75001.00;
            Assert.AreEqual(0.40, investor.TaxRate);
            investor.Income = 84526.00;
            Assert.AreEqual(0.40, investor.TaxRate);
            investor.Income = 150000.99;
            Assert.AreEqual(0.40, investor.TaxRate);

            investor.Income = 150001.00;
            Assert.AreEqual(0.45, investor.TaxRate);
            investor.Income = 205456.44;
            Assert.AreEqual(0.45, investor.TaxRate);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(0.45, investor.TaxRate);
        }

        [Test]
        public void TaxLiabilityCalculatedCorrectlyForAustralia()
        {
            // Create the instance of the investor
            IInvestor investor = new AustralianInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 1500.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 6000.99;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);

            investor.Income = 6001.00;
            Assert.AreEqual(0.15, investor.TaxLiability, 2.0);
            investor.Income = 22258.32;
            Assert.AreEqual(2438.60, investor.TaxLiability, 2.0);
            investor.Income = 25000.99;
            Assert.AreEqual(2850.00, investor.TaxLiability, 2.0);

            investor.Income = 25001.00;
            Assert.AreEqual(2850.00, investor.TaxLiability, 2.0);
            investor.Income = 65000.00;
            Assert.AreEqual(14849.70, investor.TaxLiability, 2.0);
            investor.Income = 75000.99;
            Assert.AreEqual(17850.00, investor.TaxLiability, 2.0);

            investor.Income = 75001.00;
            Assert.AreEqual(17850.00, investor.TaxLiability, 2.0);
            investor.Income = 84526.00;
            Assert.AreEqual(21660.00, investor.TaxLiability, 2.0);
            investor.Income = 150000.99;
            Assert.AreEqual(47850.00, investor.TaxLiability, 2.0);

            investor.Income = 150001.00;
            Assert.AreEqual(47850.00, investor.TaxLiability, 2.0);
            investor.Income = 205456.44;
            Assert.AreEqual(72804.94, investor.TaxLiability, 2.0);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(8.0896191068804208E+307, investor.TaxLiability, 2.0);
        }

        [Test]
        public void TaxRateCalculatedCorrectlyForNewZealand()
        {
            // Create the instance of the investor
            IInvestor investor = new NewZealandInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.195, investor.TaxRate);
            investor.Income = 9500.00;
            Assert.AreEqual(0.195, investor.TaxRate);
            investor.Income = 19500.00;
            Assert.AreEqual(0.195, investor.TaxRate);
            investor.Income = 19500.99;
            Assert.AreEqual(0.195, investor.TaxRate);

            investor.Income = 19501.00;
            Assert.AreEqual(0.33, investor.TaxRate);
            investor.Income = 28000.00;
            Assert.AreEqual(0.33, investor.TaxRate);
            investor.Income = 60000.00;
            Assert.AreEqual(0.33, investor.TaxRate);
            investor.Income = 60000.99;
            Assert.AreEqual(0.33, investor.TaxRate);

            investor.Income = 60001.00;
            Assert.AreEqual(0.39, investor.TaxRate);
            investor.Income = 65000.00;
            Assert.AreEqual(0.39, investor.TaxRate);
            investor.Income = 999999999.00;
            Assert.AreEqual(0.39, investor.TaxRate);
        }

        [Test]
        public void TaxLiabilityCalculatedCorrectlyForNewZealand()
        {
            // Create the instance of the investor
            IInvestor investor = new NewZealandInvestor(0.0);

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 9500.00;
            Assert.AreEqual(1852.50, investor.TaxLiability, 2.0);
            investor.Income = 19500.00;
            Assert.AreEqual(3802.50, investor.TaxLiability, 2.0);
            investor.Income = 19500.99;
            Assert.AreEqual(3802.69, investor.TaxLiability, 2.0);

            investor.Income = 19501.00;
            Assert.AreEqual(3802.70, investor.TaxLiability, 2.0);
            investor.Income = 28000.00;
            Assert.AreEqual(6607.36, investor.TaxLiability, 2.0);
            investor.Income = 60000.00;
            Assert.AreEqual(17167.36, investor.TaxLiability, 2.0);
            investor.Income = 60000.99;
            Assert.AreEqual(17167.69, investor.TaxLiability, 2.0);

            investor.Income = 60001.00;
            Assert.AreEqual(17167.69, investor.TaxLiability, 2.0);
            investor.Income = 65000.00;
            Assert.AreEqual(19117.30, investor.TaxLiability, 2.0);
            investor.Income = 999999999.00;
            Assert.AreEqual(389993766.91, investor.TaxLiability, 2.0);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(7.0110032259630313E+307, investor.TaxLiability, 2.0);
        }

        [Test]
        public void TaxRateCalculatedCorrectlyForNonExceptionalBehavior()
        {
            // Create the instance of the investor for Non-Exceptional behavior
            IInvestor investor = new NullInvestor();

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 9500.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 19500.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 19500.99;
            Assert.AreEqual(0.0, investor.TaxRate);

            investor.Income = 19501.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 28000.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 60000.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 60000.99;
            Assert.AreEqual(0.0, investor.TaxRate);

            investor.Income = 60001.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 65000.00;
            Assert.AreEqual(0.0, investor.TaxRate);
            investor.Income = 999999999.00;
            Assert.AreEqual(0.0, investor.TaxRate);
        }

        [Test]
        public void TaxLiabilityCalculatedCorrectlyForNonExceptionalBehavior()
        {
            // Create the instance of the investor for Non-Exceptional behavior
            IInvestor investor = new NullInvestor();

            // Validate the calculations works as expected

            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 9500.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 19500.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 19500.99;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);

            investor.Income = 19501.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 28000.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 60000.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 60000.99;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);

            investor.Income = 60001.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 65000.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = 999999999.00;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
            investor.Income = double.MaxValue - 0.01;
            Assert.AreEqual(0.0, investor.TaxLiability, 2.0);
        }
    }
}

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This article, along with any associated source code and files, is licensed under The MIT License


Written By
Maruis Marais
Web Developer
New Zealand New Zealand
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

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Posted 20 Nov 2006

Article Copyright 2006 by Maruis Marais
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