public void Items_ReturnsKeyValuePairForEveryItemInTheMultiValueDictionary()
        {
            var source = new[]
            {
                new KeyValuePair <string, string>("A", "A"),
                new KeyValuePair <string, string>("A", "B"),
                new KeyValuePair <string, string>("A", "C"),
                new KeyValuePair <string, string>("B", "A"),
                new KeyValuePair <string, string>("B", "B"),
                new KeyValuePair <string, string>("C", "A")
            };

            foreach (var kvp in source)
            {
                _target.Add(kvp.Key, kvp.Value);
            }

            var result = _target.Items();

            Assert.All(result, itm => source.Contains(itm));
            Assert.All(source, itm => result.Contains(itm));
        }