public void ClearTest()
        {
            var bi = new BiDirectionalDictionary <int, int> {
                { 1, 1 }, { 2, 2 }
            };

            bi.Clear();
            Assert.AreEqual(0, bi.Count);
        }
        public void BiDirectionalDictionaryCount()

        {
            var bi = new BiDirectionalDictionary <int, int>();

            Assert.AreEqual(0, bi.Count);
            bi.Add(1, 1);
            Assert.AreEqual(1, bi.Count);
            bi.Add(2, 2);
            Assert.AreEqual(2, bi.Count);
            bi.Clear();
            Assert.AreEqual(0, bi.Count);
        }