Nucleotide count implementation

nucleotide-count/Example.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+
+public class DNA
+{
+    public IDictionary<char, int> NucleotideCounts { get; private set; }
+
+    public DNA(string sequence)
+    {
+        InitializeNucleotideCounts(sequence);
+    }
+
+    private void InitializeNucleotideCounts(string sequence)
+    {
+        NucleotideCounts = new Dictionary<char, int> { { 'A', 0 }, { 'T', 0 }, { 'C', 0 }, { 'G', 0 } };
+        foreach (var s in sequence)
+            NucleotideCounts[s] += 1;
+    }
+
+    public int Count(char nucleotide)
+    {
+        if (IsUracil(nucleotide))
+            return 0;
+
+        int count;
+        if (!NucleotideCounts.TryGetValue(nucleotide, out count))
+            throw new InvalidNucleotideException();
+        return count;
+    }
+
+    private static bool IsUracil(char nucleotide)
+    {
+        return nucleotide == 'U';
+    }
+}
+
+public class InvalidNucleotideException : Exception { }

nucleotide-count/NucleotideCountTest.cs

@@ -0,0 +1,73 @@
+using System.Collections.Generic;
+using NUnit.Framework;
+
+[TestFixture]
+public class NucleoTideCountTest
+{
+    [Test]
+    public void HasNoNucleotides()
+    {
+        var dna = new DNA("");
+        var expected = new Dictionary<char, int> { { 'A', 0 }, { 'T', 0 }, { 'C', 0 }, { 'G', 0 } };
+        Assert.That(dna.NucleotideCounts, Is.EquivalentTo(expected));
+    }
+
+    [Test]
+    public void HasNoAdenosine()
+    {
+        var dna = new DNA("");
+        Assert.That(dna.Count('A'), Is.EqualTo(0));
+    }
+
+    [Test]
+    public void RepetitiveCytidineGetsCounts()
+    {
+        var dna = new DNA("CCCCC");
+        Assert.That(dna.Count('C'), Is.EqualTo(5));
+    }
+
+    [Test]
+    public void RepetitiveSequenceHasOnlyGuanosine()
+    {
+        var dna = new DNA("GGGGGGGG");
+        var expected = new Dictionary<char, int> { { 'A', 0 }, { 'T', 0 }, { 'C', 0 }, { 'G', 8 } };
+        Assert.That(dna.NucleotideCounts, Is.EquivalentTo(expected));
+    }
+
+    [Test]
+    public void CountsOnlyThymidine()
+    {
+        var dna = new DNA("GGGGTAACCCGG");
+        Assert.That(dna.Count('T'), Is.EqualTo(1));
+    }
+
+    [Test]
+    public void CountsANucleotideOnlyOnce()
+    {
+        var dna = new DNA("GGTTGG");
+        dna.Count('T');
+        Assert.That(dna.Count('T'), Is.EqualTo(2));
+    }
+
+    [Test]
+    public void HasNoUracil()
+    {
+        var dna = new DNA("GGTTGG");
+        Assert.That(dna.Count('U'), Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ValidatesNucleotides()
+    {
+        var dna = new DNA("GGTTGG");
+        Assert.Throws<InvalidNucleotideException>(() => dna.Count('X'));
+    }
+
+    [Test]
+    public void CountsAllNucleotides()
+    {
+        var dna = new DNA("AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC");
+        var expected = new Dictionary<char, int> { { 'A', 20 }, { 'T', 21 }, { 'C', 12 }, { 'G', 17 } };
+        Assert.That(dna.NucleotideCounts, Is.EquivalentTo(expected));
+    }
+}

word-count/WordCountTest.cs

@@ -2,7 +2,7 @@
 using NUnit.Framework;
 
 [TestFixture]
-public class BobTest
+public class WordCountTest
 {
     [Test]
     public void CountOneWord ()