Make exercise APIs more C#-like

If a problem doesn't necessarily need to contain state, C# classes should
utilize the static keyword to make the class a repository of static methods.
This allows for easier LINQ-chaining and is generally better for concurrent
programming.
Updated tests and examples to match new APIs.

Author: bressain

binary/BinaryTest.cs

@@ -13,7 +13,7 @@ public class BinaryTest
     [TestCase("10001101000", Result = 1128, Ignore = true)]
     public int Binary_converts_to_decimal(string binary)
     {
-        return new Binary(binary).ToDecimal();
+        return Binary.ToDecimal(binary);
     }
 
     [TestCase("carrot", Ignore = true)]
@@ -24,13 +24,13 @@ public int Binary_converts_to_decimal(string binary)
     [TestCase("abc10z", Ignore = true)]
     public void Invalid_binary_is_decimal_0(string invalidValue)
     {
-        Assert.That(new Binary(invalidValue).ToDecimal(), Is.EqualTo(0));
+        Assert.That(Binary.ToDecimal(invalidValue), Is.EqualTo(0));
     }
 
     [Ignore]
     [Test]
     public void Binary_can_convert_formatted_strings()
     {
-        Assert.That(new Binary("011").ToDecimal(), Is.EqualTo(3));
+        Assert.That(Binary.ToDecimal("011"), Is.EqualTo(3));
     }
 }

binary/Example.cs

@@ -3,25 +3,18 @@
 
 public class Binary
 {
-    private readonly string value;
-
-    public Binary(string value)
-    {
-        this.value = value;
-    }
-
-    public int ToDecimal()
+    public static int ToDecimal(string binary)
     {
-        if (IsNotValidBinary()) return 0;
+        if (IsNotValidBinary(binary)) return 0;
 
-        return value
-            .Select((c, i) => int.Parse(c.ToString()) * TwoToThePowerOf(value.Length - i - 1))
+        return binary
+            .Select((c, i) => int.Parse(c.ToString()) * TwoToThePowerOf(binary.Length - i - 1))
             .Sum();
     }
 
-    private bool IsNotValidBinary()
+    private static bool IsNotValidBinary(string binary)
     {
-        return !value.All(x => char.IsDigit(x) && int.Parse(x.ToString()) < 2);
+        return !binary.All(x => char.IsDigit(x) && int.Parse(x.ToString()) < 2);
     }
 
     private static int TwoToThePowerOf(int power)

bob/BobTest.cs

@@ -3,136 +3,128 @@
 [TestFixture]
 public class BobTest
 {
-    private Bob teenager;
-
-    [SetUp]
-    public void Init ()
-    {
-        teenager = new Bob();
-    }
-
     [Test]
     public void Stating_something ()
     {
-        Assert.That(teenager.Hey("Tom-ay-to, tom-aaaah-to."), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("Tom-ay-to, tom-aaaah-to."), Is.EqualTo("Whatever."));
     }
 
     [Ignore]
     [Test]
     public void Shouting ()
     {
-        Assert.That(teenager.Hey("WATCH OUT!"), Is.EqualTo("Whoa, chill out!"));
+        Assert.That(Bob.Hey("WATCH OUT!"), Is.EqualTo("Whoa, chill out!"));
     }
 
     [Ignore]
     [Test]
     public void Asking_a_question ()
     {
-        Assert.That(teenager.Hey("Does this cryogenic chamber make me look fat?"), Is.EqualTo("Sure."));
+        Assert.That(Bob.Hey("Does this cryogenic chamber make me look fat?"), Is.EqualTo("Sure."));
     }
 
     [Ignore]
     [Test]
     public void Asking_a_question_with_a_trailing_space()
     {
-        Assert.That(teenager.Hey("Do I like my  spacebar  too much?  "), Is.EqualTo("Sure."));
+        Assert.That(Bob.Hey("Do I like my  spacebar  too much?  "), Is.EqualTo("Sure."));
     }
 
     [Ignore]
     [Test]
     public void Asking_a_numeric_question ()
     {
-        Assert.That(teenager.Hey("You are, what, like 15?"), Is.EqualTo("Sure."));
+        Assert.That(Bob.Hey("You are, what, like 15?"), Is.EqualTo("Sure."));
     }
 
     [Ignore]
     [Test]
     public void Talking_forcefully ()
     {
-        Assert.That(teenager.Hey("Let's go make out behind the gym!"), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("Let's go make out behind the gym!"), Is.EqualTo("Whatever."));
     }
 
     [Ignore]
     [Test]
     public void Using_acronyms_in_regular_search ()
     {
-        Assert.That(teenager.Hey("It's OK if you don't want to go to the DMV."), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("It's OK if you don't want to go to the DMV."), Is.EqualTo("Whatever."));
     }
 
     [Ignore]
     [Test]
     public void Forceful_questions ()
     {
-        Assert.That(teenager.Hey("WHAT THE HELL WERE YOU THINKING?"), Is.EqualTo("Whoa, chill out!"));
+        Assert.That(Bob.Hey("WHAT THE HELL WERE YOU THINKING?"), Is.EqualTo("Whoa, chill out!"));
     }
 
     [Ignore]
     [Test]
     public void Shouting_numbers ()
     {
-        Assert.That(teenager.Hey("1, 2, 3 GO!"), Is.EqualTo("Whoa, chill out!"));
+        Assert.That(Bob.Hey("1, 2, 3 GO!"), Is.EqualTo("Whoa, chill out!"));
     }
 
     [Ignore]
     [Test]
     public void Only_numbers ()
     {
-        Assert.That(teenager.Hey("1, 2, 3"), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("1, 2, 3"), Is.EqualTo("Whatever."));
     }
 
     [Ignore]
     [Test]
     public void Question_with_only_numbers ()
     {
-        Assert.That(teenager.Hey("4?"), Is.EqualTo("Sure."));
+        Assert.That(Bob.Hey("4?"), Is.EqualTo("Sure."));
     }
 
     [Ignore]
     [Test]
     public void Shouting_with_special_characters ()
     {
-        Assert.That(teenager.Hey("ZOMG THE %^*@#$(*^ ZOMBIES ARE COMING!!11!!1!"), Is.EqualTo("Whoa, chill out!"));
+        Assert.That(Bob.Hey("ZOMG THE %^*@#$(*^ ZOMBIES ARE COMING!!11!!1!"), Is.EqualTo("Whoa, chill out!"));
     }
 
     [Ignore]
     [Test]
     public void Shouting_with_no_exclamation_mark ()
     {
-        Assert.That(teenager.Hey("I HATE YOU"), Is.EqualTo("Whoa, chill out!"));
+        Assert.That(Bob.Hey("I HATE YOU"), Is.EqualTo("Whoa, chill out!"));
     }
 
     [Ignore]
     [Test]
     public void Statement_containing_question_mark ()
     {
-        Assert.That(teenager.Hey("Ending with ? means a question."), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("Ending with ? means a question."), Is.EqualTo("Whatever."));
     }
 
     [Ignore]
     [Test]
     public void Prattling_on ()
     {
-        Assert.That(teenager.Hey("Wait! Hang on. Are you going to be OK?"), Is.EqualTo("Sure."));
+        Assert.That(Bob.Hey("Wait! Hang on. Are you going to be OK?"), Is.EqualTo("Sure."));
     }
 
     [Ignore]
     [Test]
     public void Silence ()
     {
-        Assert.That(teenager.Hey(""), Is.EqualTo("Fine. Be that way!"));
+        Assert.That(Bob.Hey(""), Is.EqualTo("Fine. Be that way!"));
     }
 
     [Ignore]
     [Test]
     public void Prolonged_silence ()
     {
-        Assert.That(teenager.Hey("    "), Is.EqualTo("Fine. Be that way!"));
+        Assert.That(Bob.Hey("    "), Is.EqualTo("Fine. Be that way!"));
     }
 
     [Ignore]
     [Test]
     public void Multiple_line_question ()
     {
-        Assert.That(teenager.Hey("Does this cryogenic chamber make me look fat?\nno"), Is.EqualTo("Whatever."));
+        Assert.That(Bob.Hey("Does this cryogenic chamber make me look fat?\nno"), Is.EqualTo("Whatever."));
     }
 }

bob/Example.cs

@@ -1,38 +1,27 @@
 public class Bob
 {
-    public string Hey(string statement)
+    public static string Hey(string statement)
     {
-
         if (IsSilence(statement))
-        {
             return "Fine. Be that way!";
-        }
         if (IsYelling(statement))
-        {
             return "Whoa, chill out!";
-        }
         if (IsQuestion(statement))
-        {
             return "Sure.";
-        }
-        else
-        {
-            return "Whatever.";
-        }
-
+        return "Whatever.";
     }
 
-    private bool IsSilence (string statement)
+    private static bool IsSilence (string statement)
     {
         return statement.Trim() == "";
     }
 
-    private bool IsYelling (string statement)
+    private static bool IsYelling (string statement)
     {
         return statement.ToUpper() == statement && System.Text.RegularExpressions.Regex.IsMatch(statement, "[a-zA-Z]+");
     }
 
-    private bool IsQuestion (string statement)
+    private static bool IsQuestion (string statement)
     {
         return statement.Trim().EndsWith("?");
     }

gigasecond/Example.cs

@@ -2,14 +2,7 @@
 
 public class Gigasecond
 {
-    private readonly DateTime birthDate;
-
-    public Gigasecond(DateTime birthDate)
-    {
-        this.birthDate = birthDate;
-    }
-
-    public DateTime Date()
+    public static DateTime Date(DateTime birthDate)
     {
         return birthDate.AddSeconds(1000000000);
     }

gigasecond/GigasecondTest.cs

@@ -7,23 +7,23 @@ public class GigasecondTest
     [Test]
     public void First_date()
     {
-        var gs = new Gigasecond(new DateTime(2011, 4, 25, 0, 0, 0, DateTimeKind.Utc));
-        Assert.That(gs.Date(), Is.EqualTo(new DateTime(2043, 1, 1, 1, 46, 40, DateTimeKind.Utc)));
+        var date = Gigasecond.Date(new DateTime(2011, 4, 25, 0, 0, 0, DateTimeKind.Utc));
+        Assert.That(date, Is.EqualTo(new DateTime(2043, 1, 1, 1, 46, 40, DateTimeKind.Utc)));
     }
 
     [Test]
     [Ignore]
     public void Another_date()
     {
-        var gs = new Gigasecond(new DateTime(1977, 6, 13, 0, 0, 0, DateTimeKind.Utc));
-        Assert.That(gs.Date(), Is.EqualTo(new DateTime(2009, 2, 19, 1, 46, 40, DateTimeKind.Utc)));
+        var date = Gigasecond.Date(new DateTime(1977, 6, 13, 0, 0, 0, DateTimeKind.Utc));
+        Assert.That(date, Is.EqualTo(new DateTime(2009, 2, 19, 1, 46, 40, DateTimeKind.Utc)));
     }
 
     [Test]
     [Ignore]
     public void Yet_another_date()
     {
-        var gs = new Gigasecond(new DateTime(1959, 7, 19, 0, 0, 0, DateTimeKind.Utc));
-        Assert.That(gs.Date(), Is.EqualTo(new DateTime(1991, 3, 27, 1, 46, 40, DateTimeKind.Utc)));
+        var date = Gigasecond.Date(new DateTime(1959, 7, 19, 0, 0, 0, DateTimeKind.Utc));
+        Assert.That(date, Is.EqualTo(new DateTime(1991, 3, 27, 1, 46, 40, DateTimeKind.Utc)));
     }
 }

octal/Example.cs

@@ -3,25 +3,18 @@
 
 public class Octal
 {
-    private readonly string value;
-
-    public Octal(string value)
-    {
-        this.value = value;
-    }
-
-    public int ToDecimal()
+    public static int ToDecimal(string octal)
     {
-        if (IsNotValidOctal()) return 0;
+        if (IsNotValidOctal(octal)) return 0;
 
-        return value
-            .Select((c, i) => int.Parse(c.ToString()) * EightToThePowerOf(value.Length - i - 1))
+        return octal
+            .Select((c, i) => int.Parse(c.ToString()) * EightToThePowerOf(octal.Length - i - 1))
             .Sum();
     }
 
-    private bool IsNotValidOctal()
+    private static bool IsNotValidOctal(string octal)
     {
-        return !value.All(x => char.IsDigit(x) && int.Parse(x.ToString()) < 8);
+        return !octal.All(x => char.IsDigit(x) && int.Parse(x.ToString()) < 8);
     }
 
     private static int EightToThePowerOf(int power)

octal/OctalTest.cs

@@ -14,7 +14,7 @@ public class OctalTest
     [TestCase("1234567", Result = 342391, Ignore = true)]
     public int Octal_converts_to_decimal(string value)
     {
-        return new Octal(value).ToDecimal();
+        return Octal.ToDecimal(value);
     }
 
     [TestCase("carrot", Ignore = true)]
@@ -24,13 +24,13 @@ public int Octal_converts_to_decimal(string value)
     [TestCase("abc1z", Ignore = true)]
     public void Invalid_octal_is_decimal_0(string invalidValue)
     {
-        Assert.That(new Octal(invalidValue).ToDecimal(), Is.EqualTo(0));
+        Assert.That(Octal.ToDecimal(invalidValue), Is.EqualTo(0));
     }
 
     [Ignore]
     [Test]
     public void Octal_can_convert_formatted_strings()
     {
-        Assert.That(new Octal("011").ToDecimal(), Is.EqualTo(9));
+        Assert.That(Octal.ToDecimal("011"), Is.EqualTo(9));
     }
 }

scrabble-score/Example.cs

@@ -3,8 +3,6 @@
 
 public class Scrabble
 {
-    private readonly string word;
-
     private static readonly Dictionary<char, int> LetterScores = new Dictionary<char, int>
         {
             { 'a', 1 }, { 'e', 1 }, { 'i', 1 }, { 'o', 1 }, { 'u', 1 }, { 'l', 1 }, { 'n', 1 }, { 'r', 1 }, { 's', 1 }, { 't', 1 },
@@ -16,21 +14,11 @@ public class Scrabble
             { 'q', 10 }, { 'z', 10 }
         };
 
-    public Scrabble(string word)
-    {
-        this.word = word;
-    }
-
     public static int Score(string input)
     {
         if (string.IsNullOrWhiteSpace(input))
             return 0;
 
         return input.ToLower().Sum(x => LetterScores[x]);
     }
-
-    public int Score()
-    {
-        return Score(word);
-    }
 }