Working on ranking a list of reviewers with respect to a single revie…

…wer. This is being implemented with PearsonCorrelation and will be improved later to work with any SimilarityScore algorithm.

Recommender.Tests/RankReviewersTests.cs

@@ -0,0 +1,71 @@
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using Recommender.Data;
+using Recommender.Reviews;
+
+namespace Recommender.Tests
+{
+    [TestFixture]
+    class RankReviewersTests
+    {
+        private List<Reviewer> reviewers;
+        IOrderedEnumerable<KeyValuePair<Reviewer, double>> sortedReviewers;
+        private RankReviewers rankReviewers;
+
+        [SetUp]
+        public void SetUp()
+        {
+            var currentUser = BuildCurrentUser();
+            reviewers = BuildReviewers();
+
+            sortedReviewers = new RankReviewers(BuildCurrentUser(), BuildReviewers()).Rank();
+        }
+
+        private List<Reviewer> BuildReviewers()
+        {
+            return new List<Reviewer>
+                        {
+                            {ReviewerBuilder.BuildReviewer2()},
+                            {ReviewerBuilder.BuildReviewer3()},
+                            {ReviewerBuilder.BuildReviewer4()},
+                            {ReviewerBuilder.BuildReviewer5()},
+                        };
+        }
+
+        private static Reviewer BuildCurrentUser()
+        {
+            return ReviewerBuilder.BuildReviewer1();
+        }
+
+        [Test]
+        public void OrderingOfSortedReviewersShouldBeDifferentThanInitialListOfReviewers()
+        {
+            Assert.AreNotEqual(reviewers.First(), sortedReviewers.First().Key);
+        }
+
+        [Test]
+        public void TheMostSimilarReviewerShouldBeR4()
+        {
+            Assert.AreEqual(reviewers.ElementAt(2).Name, sortedReviewers.ElementAt(0).Key.Name);
+        }
+
+        [Test]
+        public void TheSecondRankedReviewerShouldBeR5()
+        {
+            Assert.AreEqual(reviewers.ElementAt(3).Name, sortedReviewers.ElementAt(1).Key.Name);
+        }
+
+        [Test]
+        public void TheThirdRankedReviewerShouldBeR2()
+        {
+            Assert.AreEqual(reviewers.ElementAt(0).Name, sortedReviewers.ElementAt(2).Key.Name);
+        }
+
+        [Test]
+        public void TheLeastSimilarReviewerShouldBeR3()
+        {
+            Assert.AreEqual(reviewers.ElementAt(1).Name, sortedReviewers.ElementAt(3).Key.Name);
+        }
+    }
+}

Recommender.Tests/Recommender.Tests.csproj

@@ -49,6 +49,7 @@
   <ItemGroup>
     <Compile Include="Common\FindSimilarReviewsTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="RankReviewersTests.cs" />
     <Compile Include="Reviews\ReviewerTests.cs" />
     <Compile Include="Instructions\SumProductsTests.cs" />
     <Compile Include="Instructions\SumSquaresTests.cs" />

Recommender.Tests/SimilarityScore/PearsonCorrelationTests.cs

@@ -37,5 +37,15 @@ public void TwoReviewersWithSomeSimilarReviewsShouldHaveAScoreBetweenZeroAndOne(
         {
             Assert.AreEqual(0.396, pearsonCorrelationScore.Score());
         }
+
+        [Test]
+        public void TestValuesOfReviewers()
+        {
+            var currentUser = ReviewerBuilder.BuildReviewer1();
+            Assert.AreEqual(0.396, new PearsonCorrelation(currentUser, ReviewerBuilder.BuildReviewer2()).Score());
+            Assert.AreEqual(-0.141, new PearsonCorrelation(currentUser, ReviewerBuilder.BuildReviewer3()).Score());
+            Assert.AreEqual(0.567, new PearsonCorrelation(currentUser, ReviewerBuilder.BuildReviewer4()).Score());
+            Assert.AreEqual(0.423, new PearsonCorrelation(currentUser, ReviewerBuilder.BuildReviewer5()).Score());
+        }
     }
 }

Recommender/Data/ReviewerBuilder.cs

@@ -95,10 +95,10 @@ public static Reviewer BuildReviewer2()
         public static Reviewer BuildReviewer3()
         {
             var reviewer = new Reviewer {Name = "Michael"};
-            reviewer.AddReview("Code Complete", 2.5);
-            reviewer.AddReview("C# in Depth", 3.0);
-            reviewer.AddReview("Unit Testing", 3.5);
-            reviewer.AddReview("Refactoring", 4.0);
+            reviewer.AddReview("Code Complete", 1.5);
+            reviewer.AddReview("C# in Depth", 1.0);
+            reviewer.AddReview("Unit Testing", 4.5);
+            reviewer.AddReview("Refactoring", 5.0);
             return reviewer;
         }
 

Recommender/RankReviewers.cs

@@ -0,0 +1,26 @@
+using System.Collections.Generic;
+using System.Linq;
+using Recommender.Reviews;
+using Recommender.SimilarityScore;
+
+namespace Recommender
+{
+    public class RankReviewers
+    {
+        private readonly Reviewer CurrentUser;
+        private readonly List<Reviewer> Reviewers;
+
+        public RankReviewers(Reviewer currentUser, List<Reviewer> reviewers)
+        {
+            CurrentUser = currentUser;
+            Reviewers = reviewers;
+        }
+
+        public IOrderedEnumerable<KeyValuePair<Reviewer, double>> Rank()
+        {
+            var scores = Reviewers.ToDictionary(r => r, r => new PearsonCorrelation(CurrentUser, r).Score());
+
+            return scores.OrderByDescending(key => key.Value);
+        }
+    }
+}

Recommender/Recommender.csproj

@@ -45,6 +45,7 @@
   <ItemGroup>
     <Compile Include="Common\FindSimilarReviews.cs" />
     <Compile Include="Data\ReviewerBuilder.cs" />
+    <Compile Include="RankReviewers.cs" />
     <Compile Include="Reviews\Reviewer.cs" />
     <Compile Include="SimilarityScoreRunner.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />