public void CopyTo()
        {
            Int32StringPair[] array = new Int32StringPair[4];
            Assert.Throws <ArgumentException>(() => _dictionary.CopyTo(array, 3));

            _dictionary.CopyTo(array, 0);
            for (int i = 0; i < _dictionary.Count; i++)
            {
                Assert.IsTrue(_dictionary.Contains(array[i]));
            }

            _dictionary.CopyTo(array, 1);
            for (int i = 0; i < _dictionary.Count; i++)
            {
                Assert.IsTrue(_dictionary.Contains(array[i + 1]));
            }
        }
 public void CopyToEmpty()
 {
     _dictionary.Clear();
     Int32StringPair[] array = new Int32StringPair[0];
     _dictionary.CopyTo(array, 0);
 }