RankListTesst.cs (tests added), Score.cs modified

RankListTests.cs
public void TestSaveToFile_ShouldSave_ThreeScores()
public void TestSaveToFile_ShouldSave_TenScores()

Score.cs
+        public override bool Equals(object obj)
+        {
+            if (!(obj is Score))
+            {
+                return false;
+            }
+
+            Score objAsScore = obj as Score;
+
+            if (this.Nickname == objAsScore.Nickname &&
+                this.Attempts == objAsScore.Attempts)
+            {
+                return true;
+            }
+
+            return false;
+        }