public void Should_Return_Zero_Euclidean_Distance_When_Entities_Have_No_Preferences_In_Common() { const string entity1 = "Lisa Rose"; const string entity2 = "Gene Seymour"; var entity1Preferences = new Dictionary <string, double> { { "Lady in the Water", 2.5 }, { "Snakes on a Plane", 3.5 }, { "Just My Luck", 3.0 } }; var entity2Preferences = new Dictionary <string, double> { { "Superman Returns", 5 }, { "You, Me and Dupree", 3.5 }, { "The Night Listener", 3.0 } }; var preferences = new Dictionary <string, Dictionary <string, double> > { { entity1, entity1Preferences }, { entity2, entity2Preferences } }; var sim = new Similarity <string, string>(); var result = sim.GetSimilarityByEuclideanDistance(preferences, entity1, entity2); Assert.AreEqual(result, 0); }