public void Circle()
 {
     DependencyMap<string> map = new DependencyMap<string>();
     map.Add("A", "B");
     map.Add("B", "C");
     map.Add("C", "A");
     map.SortDependencies();
 }
 private void CheckSort(string expected, DependencyMap<string> map)
 {
     IEnumerable<string> sorted = map.SortDependencies();
     string s = sorted.Aggregate("", (seed, item) => seed + item);
     Assert.AreEqual(expected, s);
 }
 public void Empty()
 {
     DependencyMap<string> map = new DependencyMap<string>();
     IEnumerable<string> sorted = map.SortDependencies();
     Assert.AreEqual(0, sorted.Count());
 }