update cs/ch17-04 README. Clean up code to have zero SonarQube squawks

bgruenba · bgruenba · commit cbaa66a6fb9c · 2025-09-21T10:17:54.000-07:00
diff --git a/cs/ch17-01-tests/Money.Tests/CurrencyPairTest.cs b/cs/ch17-01-tests/Money.Tests/CurrencyPairTest.cs
@@ -1,3 +1,5 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
 #region TO DO's
@@ -12,6 +14,7 @@ public class CurrencyPairTest
     [TestCase("ZAR", "USD", TestName = "CurrencyPair ZAR to USD are equal")]
     [TestCase("CHF", "USD", false, TestName = "CurrencyPair CHF to USD != USD to CHF")]
     [TestCase("ZAR", "USD", false, TestName = "CurrencyPair ZAR to USD != USD to ZAR")]
+    [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]
     public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     {
         var pair = new CurrencyPair(from, to);
@@ -34,8 +37,8 @@ public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     public void TestEdgeCases(string from, string to)
     {
         var pair = new CurrencyPair(from, to);
-        Assert.That(pair, Is.Not.EqualTo(null));
+        Assert.That(pair, Is.Not.Null);
         Assert.That(pair, Is.Not.EqualTo(new object()));
-        Assert.That(pair, Is.EqualTo(pair));
+        Assert.That(pair, Is.EqualTo(new CurrencyPair(from, to)));
     }
 }
diff --git a/cs/ch17-01-tests/Money.Tests/MoneyTest.cs b/cs/ch17-01-tests/Money.Tests/MoneyTest.cs
@@ -53,18 +53,10 @@ public static Func<int, Money> GetCurrencyFactory(string currency)
         return _currencyFactories[currency];
     }
 
-    private Money? _fiveDollar;
-    
     [SetUp]
     public void Setup()
     {
-        _fiveDollar = Money.Dollar(5);
-    }
-
-    [TearDown]
-    public void TearDown()
-    {
-        _fiveDollar = null;
+        // No setup needed.
     }
 
     [TestCase("USD", 5, 5, TestName = "construct USD 5")]
diff --git a/cs/ch17-01-tests/Money/Bank.cs b/cs/ch17-01-tests/Money/Bank.cs
@@ -2,7 +2,7 @@ namespace TheSoftwareGorilla.TDD.Money;
 
 public class Bank
 {
-    private Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();
+    private readonly Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();
     public Money Reduce(Expression source, string to)
     {
         return source.Reduce(this, to);
diff --git a/cs/ch17-01-tests/Money/Expression.cs b/cs/ch17-01-tests/Money/Expression.cs
@@ -1,5 +1,8 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace TheSoftwareGorilla.TDD.Money;
 
+[SuppressMessage("csharpsquid","S101", Justification = "Interface name exists for parity with book examples.")]
 public interface Expression
 {
     Money Reduce(Bank bank, string to);
diff --git a/cs/ch17-02-plus/Money.Tests/CurrencyPairTest.cs b/cs/ch17-02-plus/Money.Tests/CurrencyPairTest.cs
@@ -1,3 +1,5 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
 #region TO DO's
@@ -12,6 +14,7 @@ public class CurrencyPairTest
     [TestCase("ZAR", "USD", TestName = "CurrencyPair ZAR to USD are equal")]
     [TestCase("CHF", "USD", false, TestName = "CurrencyPair CHF to USD != USD to CHF")]
     [TestCase("ZAR", "USD", false, TestName = "CurrencyPair ZAR to USD != USD to ZAR")]
+    [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]
     public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     {
         var pair = new CurrencyPair(from, to);
@@ -34,8 +37,8 @@ public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     public void TestEdgeCases(string from, string to)
     {
         var pair = new CurrencyPair(from, to);
-        Assert.That(pair, Is.Not.EqualTo(null));
+        Assert.That(pair, Is.Not.Null);
         Assert.That(pair, Is.Not.EqualTo(new object()));
-        Assert.That(pair, Is.EqualTo(pair));
+        Assert.That(pair, Is.EqualTo(new CurrencyPair(from, to)));
     }
 }
diff --git a/cs/ch17-02-plus/Money/Bank.cs b/cs/ch17-02-plus/Money/Bank.cs
@@ -2,7 +2,7 @@ namespace TheSoftwareGorilla.TDD.Money;
 
 public class Bank
 {
-    private Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();
+    private readonly Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();
     public Money Reduce(Expression source, string to)
     {
         return source.Reduce(this, to);
diff --git a/cs/ch17-02-plus/README.md b/cs/ch17-02-plus/README.md
@@ -7,7 +7,7 @@ things:
 - Fix the "Return `Money` from \$5 + \$5" TODO item
 - Review the design decisions made
 
-This is solution is the second part of a four-part series that addresses these tasks. This part focuses on fixing Sum.
+This solution is the second part of a four-part series that addresses these tasks. This part focuses on fixing Sum.
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
diff --git a/cs/ch17-03-decimal/Money.Tests/CurrencyPairTest.cs b/cs/ch17-03-decimal/Money.Tests/CurrencyPairTest.cs
@@ -1,3 +1,5 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
 #region TO DO's
@@ -12,6 +14,7 @@ public class CurrencyPairTest
     [TestCase("ZAR", "USD", TestName = "CurrencyPair ZAR to USD are equal")]
     [TestCase("CHF", "USD", false, TestName = "CurrencyPair CHF to USD != USD to CHF")]
     [TestCase("ZAR", "USD", false, TestName = "CurrencyPair ZAR to USD != USD to ZAR")]
+    [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]
     public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     {
         var pair = new CurrencyPair(from, to);
@@ -34,8 +37,8 @@ public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     public void TestEdgeCases(string from, string to)
     {
         var pair = new CurrencyPair(from, to);
-        Assert.That(pair, Is.Not.EqualTo(null));
+        Assert.That(pair, Is.Not.Null);
         Assert.That(pair, Is.Not.EqualTo(new object()));
-        Assert.That(pair, Is.EqualTo(pair));
+        Assert.That(pair, Is.EqualTo(new CurrencyPair(from, to)));
     }
 }
diff --git a/cs/ch17-03-decimal/Money.Tests/CurrencyTransactionTest.cs b/cs/ch17-03-decimal/Money.Tests/CurrencyTransactionTest.cs
@@ -1,13 +1,6 @@
 
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
-#region TO DO's
-//TODO: Add support for subtracting two Money objects
-//TODO: Clean up the settle() method in CurrencyTransaction
-//TODO: Change the tests to do more assert expected value calculations
-//TODO: Add 5 test cases
-//TODO: Refactor the tests for separating the asserts
-#endregion
 [TestFixture]
 [Description("CurrencyTransactionTest class")]
 public class CurrencyTransactionTest
diff --git a/cs/ch17-03-decimal/Money/CurrencyTransaction.cs b/cs/ch17-03-decimal/Money/CurrencyTransaction.cs
@@ -1,5 +1,3 @@
-using System.Net;
-
 namespace TheSoftwareGorilla.TDD.Money;
 
 public class CurrencyTransaction
diff --git a/cs/ch17-03-decimal/README.md b/cs/ch17-03-decimal/README.md
@@ -7,11 +7,12 @@ things:
 - Fix the "Return `Money` from \$5 + \$5" TODO item - Done in ch17-02
 - Review the design decisions made
 
-This is solution is the second part of a four-part series that addresses these tasks. This part focuses on fixing Sum.
+This solution is the third part of a four-part series that addresses these tasks. This part focuses on converting
+the `Money.Amount` property to a `decimal` and building the `CurrencyTransaction`.
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
-## Chapter 17 - Part 3 - Decimal Floating Point Arithmetic
+## Chapter 17 - Part 3 - Switching to `decimal` Amounts
 Once I completed the action items at the beginning of Chapter 17, there was one item left I had to fix - Money rounding.
 This was the point at which I really needed to fix the decimal issue, too. 
 
diff --git a/cs/ch17-04-arithmetic/Money.Tests/CurrencyPairTest.cs b/cs/ch17-04-arithmetic/Money.Tests/CurrencyPairTest.cs
@@ -1,6 +1,4 @@
-using Microsoft.VisualStudio.TestPlatform.ObjectModel;
-using NUnit.Framework;
-using TheSoftwareGorilla.TDD.Money;
+using System.Diagnostics.CodeAnalysis;
 
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
@@ -16,6 +14,7 @@ public class CurrencyPairTest
     [TestCase("ZAR", "USD", TestName = "CurrencyPair ZAR to USD are equal")]
     [TestCase("CHF", "USD", false, TestName = "CurrencyPair CHF to USD != USD to CHF")]
     [TestCase("ZAR", "USD", false, TestName = "CurrencyPair ZAR to USD != USD to ZAR")]
+    [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]
     public void TestCurrencyPairs(string from, string to, bool isEqual = true)
     {
         var pair = new CurrencyPair(from, to);
@@ -39,6 +38,7 @@ public void TestEdgeCases(string from, string to)
     {
         var pair = new CurrencyPair(from, to);
         Assert.That(pair, Is.Not.Null);
-        Assert.That(pair, Is.EqualTo(pair));
+        Assert.That(pair, Is.Not.EqualTo(new object()));
+        Assert.That(pair, Is.EqualTo(new CurrencyPair(from, to)));
     }
 }
diff --git a/cs/ch17-04-arithmetic/Money.Tests/MoneyTest.cs b/cs/ch17-04-arithmetic/Money.Tests/MoneyTest.cs
@@ -1,19 +1,12 @@
-using Microsoft.VisualStudio.TestPlatform.ObjectModel;
-using NUnit.Framework;
-using NUnit.Framework.Internal;
-using TheSoftwareGorilla.TDD.Money;
-
 namespace TheSoftwareGorilla.TDD.Money.Tests;
 
-#region TO DO's
-#endregion
 [TestFixture]
 [Description("MoneyTest class")]
 public class MoneyTest
 {
     
-    private const decimal STD_AMT = 5;
-    private const string USD = "USD";
+    private const decimal StdAmt = 5;
+    private const string Usd = "USD";
 
     private Bank<Money> _bank;
 
@@ -61,9 +54,9 @@ public void TestToString(string currency, decimal amount)
     [Category("construction")]
     public void TestEquality(string currency1, string currency2, decimal notEqualAmount)
     {
-        var money1 =  Money.From(STD_AMT, currency1, _bank);
-        var money2 =  Money.From(STD_AMT, currency2, _bank);
-        Assert.That(money1, Is.EqualTo( Money.From(STD_AMT, currency1, _bank)));
+        var money1 =  Money.From(StdAmt, currency1, _bank);
+        var money2 =  Money.From(StdAmt, currency2, _bank);
+        Assert.That(money1, Is.EqualTo( Money.From(StdAmt, currency1, _bank)));
         Assert.That(money1, Is.Not.EqualTo( Money.From(notEqualAmount, currency1, _bank)));
         Assert.That(money2, Is.Not.EqualTo(money1));
     }
@@ -74,7 +67,7 @@ public void TestEquality(string currency1, string currency2, decimal notEqualAmo
     [Category("construction")]
     public void TestCurrency(string currency)
     {
-        var money =  Money.From(STD_AMT, currency, _bank);
+        var money =  Money.From(StdAmt, currency, _bank);
         Assert.That(money.Currency, Is.EqualTo(currency));
     }
 
@@ -84,9 +77,9 @@ public void TestCurrency(string currency)
     [Category("multiplication")]
     public void TestMultiplication(string currency, decimal multiplier1, decimal multiplier2)
     {
-        var money =  Money.From(STD_AMT, currency, _bank);
-        Assert.That( Money.From(STD_AMT * multiplier1, currency, _bank), Is.EqualTo(money * multiplier1));
-        Assert.That( Money.From(STD_AMT * multiplier2, currency, _bank), Is.EqualTo(money * multiplier2));
+        var money =  Money.From(StdAmt, currency, _bank);
+        Assert.That( Money.From(StdAmt * multiplier1, currency, _bank), Is.EqualTo(money * multiplier1));
+        Assert.That( Money.From(StdAmt * multiplier2, currency, _bank), Is.EqualTo(money * multiplier2));
     }
 
     [TestCase("USD", TestName = "simple add currency USD")]
@@ -95,22 +88,22 @@ public void TestMultiplication(string currency, decimal multiplier1, decimal mul
     [Category("addition")]
     public void TestSimpleAddition(string currency)
     {
-        var money =  Money.From(STD_AMT, currency, _bank);
+        var money =  Money.From(StdAmt, currency, _bank);
         var sum = money + money;
         Assert.That(sum, Is.InstanceOf<Money>());
         Money reduced = _bank.Convert(sum, currency);
-        Assert.That(reduced, Is.EqualTo(Money.From(STD_AMT + STD_AMT, currency, _bank)));
+        Assert.That(reduced, Is.EqualTo(Money.From(StdAmt + StdAmt, currency, _bank)));
     }
 
     [Test]
     public void TestSimpleMathReturnsFromCurrency()
     {
-        Money usd = Money.From(STD_AMT, USD, _bank);
-        Money zar = Money.From(STD_AMT, "ZAR", _bank);
-        Assert.That((usd + zar).Currency, Is.EqualTo(USD));
-        Assert.That((usd - zar).Currency, Is.EqualTo(USD));
-        Assert.That((usd * 2).Currency, Is.EqualTo(USD));
-        Assert.That((usd / 2).Currency, Is.EqualTo(USD));
+        Money usd = Money.From(StdAmt, Usd, _bank);
+        Money zar = Money.From(StdAmt, "ZAR", _bank);
+        Assert.That((usd + zar).Currency, Is.EqualTo(Usd));
+        Assert.That((usd - zar).Currency, Is.EqualTo(Usd));
+        Assert.That((usd * 2).Currency, Is.EqualTo(Usd));
+        Assert.That((usd / 2).Currency, Is.EqualTo(Usd));
         Assert.That((zar + usd).Currency, Is.EqualTo("ZAR"));
         Assert.That((zar - usd).Currency, Is.EqualTo("ZAR"));
         Assert.That((zar * 2).Currency, Is.EqualTo("ZAR"));
@@ -124,8 +117,8 @@ public void TestSimpleMathReturnsFromCurrency()
     [Category("reduction")]
     public void TestReduceMoney()
     {
-        Money result = _bank.Convert( Money.From(1, USD, _bank), USD);
-        Assert.That( Money.From(1, USD, _bank), Is.EqualTo(result));
+        Money result = _bank.Convert( Money.From(1, Usd, _bank), Usd);
+        Assert.That( Money.From(1, Usd, _bank), Is.EqualTo(result));
     }
 
     [TestCase ("CHF", "USD", 0.5, 2, TestName = "reduce money mixed currency from CHF to USD, rate 0.5, amount 2")]
@@ -148,7 +141,7 @@ public void TestReduceMoneyDifferentCurrency(string fromCurrency, string toCurre
     [Category("complex arithmetic")]
     public void TestMixedAddition(string fromCurrency, decimal fromAmount, string toCurrency, decimal toAmount, decimal expected)
     {
-        testReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => to + from);
+        TestReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => to + from);
     }
 
 
@@ -159,7 +152,7 @@ public void TestMixedAddition(string fromCurrency, decimal fromAmount, string to
     [Category("complex arithmetic")]
     public void TestSumPlusMoney(string fromCurrency, decimal fromAmount, string toCurrency, decimal toAmount, decimal expected)
     {
-        testReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => to + to + from);
+        TestReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => to + to + from);
     }
 
     [TestCase ("CHF", 10, "USD", 5, 20, TestName = "times with mixed currency CHF 10 with USD 5, expected 20")]
@@ -169,10 +162,10 @@ public void TestSumPlusMoney(string fromCurrency, decimal fromAmount, string toC
     [Category("complex arithmetic")]
     public void TestSumTimes(string fromCurrency, decimal fromAmount, string toCurrency, decimal toAmount, decimal expected)
     {
-        testReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => (to + from) * 2);
+        TestReduceHarness(fromCurrency, fromAmount, toCurrency, toAmount, expected, (from, to) => (to + from) * 2);
     }
     
-    private void testReduceHarness(string from, decimal fromAmt, string to, decimal toAmt, decimal expected, Func<Money, Money, Money> operation)
+    private void TestReduceHarness(string from, decimal fromAmt, string to, decimal toAmt, decimal expected, Func<Money, Money, Money> operation)
     {
         var fromMoney = Money.From(fromAmt, from, _bank);
         var toMoney = Money.From(toAmt, to, _bank);
@@ -189,7 +182,7 @@ private void testReduceHarness(string from, decimal fromAmt, string to, decimal
     [Test]
     public void TestPlusSameCurrencyReturnsMoney()
     {
-        Money sum =  Money.From(1, USD, _bank) + Money.From(1, USD, _bank);
+        Money sum =  Money.From(1, Usd, _bank) + Money.From(1, Usd, _bank);
         Assert.That(sum, Is.InstanceOf<Money>());
     }
 
diff --git a/cs/ch17-04-arithmetic/Money/Bank.cs b/cs/ch17-04-arithmetic/Money/Bank.cs
@@ -1,4 +1,4 @@
-using System.Net;
+using System.Diagnostics.CodeAnalysis;
 
 namespace TheSoftwareGorilla.TDD.Money;
 
@@ -27,6 +27,7 @@ public decimal Rate(string from, string to)
         return rate;
     }
 
+    [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]
     public void AddRate(string from, string to, decimal rate)
     {
         if (!_rates.ContainsKey(new CurrencyPair(from, to)))
diff --git a/cs/ch17-04-arithmetic/Money/CurrencyTransaction.cs b/cs/ch17-04-arithmetic/Money/CurrencyTransaction.cs
@@ -1,5 +1,3 @@
-using System.Net;
-
 namespace TheSoftwareGorilla.TDD.Money;
 
 public class CurrencyTransaction
diff --git a/cs/ch17-04-arithmetic/Money/ICurrencyConverter.cs b/cs/ch17-04-arithmetic/Money/ICurrencyConverter.cs
@@ -1,4 +1,3 @@
-
 namespace TheSoftwareGorilla.TDD.Money;
 
 public interface ICurrencyConverter<T> where T : ICurrencyHolder<T>
diff --git a/cs/ch17-04-arithmetic/Money/ICurrencyHolder.cs b/cs/ch17-04-arithmetic/Money/ICurrencyHolder.cs
@@ -1,6 +1,3 @@
-using System.Runtime;
-using TheSoftwareGorilla.TDD.Money;
-
 namespace TheSoftwareGorilla.TDD.Money;
 public interface ICurrencyHolder<T> where T : ICurrencyHolder<T>
 
diff --git a/cs/ch17-04-arithmetic/Money/IOperation.cs b/cs/ch17-04-arithmetic/Money/IOperation.cs
@@ -1,7 +1,6 @@
-
 namespace TheSoftwareGorilla.TDD.Money;
 public interface IOperation<T> where T : ICurrencyHolder<T>
 {
  
-    public T Evaluate();
+    public T Apply();
 }
diff --git a/cs/ch17-04-arithmetic/Money/Money.cs b/cs/ch17-04-arithmetic/Money/Money.cs
@@ -1,6 +1,3 @@
-using System.Net;
-using System.Runtime.InteropServices.Marshalling;
-
 namespace TheSoftwareGorilla.TDD.Money;
 
 public class Money : ICurrencyHolder<Money>, IExpression<Money>
@@ -70,7 +67,7 @@ public virtual Money Multiply(decimal multiplier)
     protected virtual Money InvokeOperator(Money other, Func<Money, Money, Money> operation)
     {
         Operation<Money> operationInstance = new Operation<Money>(this, other, Bank, Currency, operation);
-        return operationInstance.Evaluate();
+        return operationInstance.Apply();
     }
 
     public virtual Money Convert(string to)
diff --git a/cs/ch17-04-arithmetic/Money/Operation.cs b/cs/ch17-04-arithmetic/Money/Operation.cs
diff --git a/cs/ch17-04-arithmetic/README.md b/cs/ch17-04-arithmetic/README.md

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,5 @@`
	`1`	`+using System.Diagnostics.CodeAnalysis;`
	`2`	`+`
`1`	`3`	`namespace TheSoftwareGorilla.TDD.Money.Tests;`
`2`	`4`
`3`	`5`	`#region TO DO's`
`@@ -12,6 +14,7 @@ public class CurrencyPairTest`
`12`	`14`	`[TestCase("ZAR", "USD", TestName = "CurrencyPair ZAR to USD are equal")]`
`13`	`15`	`[TestCase("CHF", "USD", false, TestName = "CurrencyPair CHF to USD != USD to CHF")]`
`14`	`16`	`[TestCase("ZAR", "USD", false, TestName = "CurrencyPair ZAR to USD != USD to ZAR")]`
	`17`	`+ [SuppressMessage("csharpsquid", "S2234", Justification = "Intentional parameter order inversion for inequality assertions.")]`
`15`	`18`	`public void TestCurrencyPairs(string from, string to, bool isEqual = true)`
`16`	`19`	`{`
`17`	`20`	`var pair = new CurrencyPair(from, to);`
`@@ -34,8 +37,8 @@ public void TestCurrencyPairs(string from, string to, bool isEqual = true)`
`34`	`37`	`public void TestEdgeCases(string from, string to)`
`35`	`38`	`{`
`36`	`39`	`var pair = new CurrencyPair(from, to);`
`37`		`- Assert.That(pair, Is.Not.EqualTo(null));`
	`40`	`+ Assert.That(pair, Is.Not.Null);`
`38`	`41`	`Assert.That(pair, Is.Not.EqualTo(new object()));`
`39`		`- Assert.That(pair, Is.EqualTo(pair));`
	`42`	`+ Assert.That(pair, Is.EqualTo(new CurrencyPair(from, to)));`
`40`	`43`	`}`
`41`	`44`	`}`
Original file line number	Diff line number	Diff line change
`@@ -53,18 +53,10 @@ public static Func<int, Money> GetCurrencyFactory(string currency)`
`53`	`53`	`return _currencyFactories[currency];`
`54`	`54`	`}`
`55`	`55`
`56`		`- private Money? _fiveDollar;`
`57`		`-`
`58`	`56`	`[SetUp]`
`59`	`57`	`public void Setup()`
`60`	`58`	`{`
`61`		`- _fiveDollar = Money.Dollar(5);`
`62`		`- }`
`63`		`-`
`64`		`- [TearDown]`
`65`		`- public void TearDown()`
`66`		`- {`
`67`		`- _fiveDollar = null;`
	`59`	`+ // No setup needed.`
`68`	`60`	`}`
`69`	`61`
`70`	`62`	`[TestCase("USD", 5, 5, TestName = "construct USD 5")]`
Original file line number	Diff line number	Diff line change
`@@ -2,7 +2,7 @@ namespace TheSoftwareGorilla.TDD.Money;`
`2`	`2`
`3`	`3`	`public class Bank`
`4`	`4`	`{`
`5`		`- private Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();`
	`5`	`+ private readonly Dictionary<CurrencyPair, int> _rates = new Dictionary<CurrencyPair, int>();`
`6`	`6`	`public Money Reduce(Expression source, string to)`
`7`	`7`	`{`
`8`	`8`	`return source.Reduce(this, to);`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,8 @@`
	`1`	`+using System.Diagnostics.CodeAnalysis;`
	`2`	`+`
`1`	`3`	`namespace TheSoftwareGorilla.TDD.Money;`
`2`	`4`
	`5`	`+[SuppressMessage("csharpsquid","S101", Justification = "Interface name exists for parity with book examples.")]`
`3`	`6`	`public interface Expression`
`4`	`7`	`{`
`5`	`8`	`Money Reduce(Bank bank, string to);`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,3 @@`
`1`		`-using System.Net;`
`2`		`-`
`3`	`1`	`namespace TheSoftwareGorilla.TDD.Money;`
`4`	`2`
`5`	`3`	`public class CurrencyTransaction`