public void TryAddTest()
        {
            var bi = new BiDirectionalDictionary <int, int> {
                { 1, 10 }, { 2, 20 }, { 3, 30 }
            };

            Assert.IsTrue(bi.TryAdd(100, 1000));
            Assert.IsFalse(bi.TryAdd(1, 15));
        }
        public void BiDirectionalDictionaryTryAdd()

        {
            var bi = new BiDirectionalDictionary <int, int> {
                { 1, 1 }, { 2, 2 }
            };

            Assert.AreEqual(2, bi.Count);
            Assert.IsTrue(bi.TryAdd(3, 3));
            Assert.AreEqual(3, bi.Count);
            Assert.IsFalse(bi.TryAdd(1, 2));
            Assert.AreEqual(3, bi.Count);
        }