//[TestMethod]
        public void TestFilterClause()
        {
            RESTUrlBuilder <ListItem> queryBuilder = new RESTUrlBuilder <ListItem>();
            string filterQuery = queryBuilder.BuildFilterClause(li => li.Id == 1);

            SPOHttpClient spoClient             = new SPOHttpClient(login, password, site);
            CollectionResponse <ListItem> items = spoClient.GetData <CollectionResponse <ListItem> >("/_api/web/lists/getByTitle('Umowy')/items?$filter=" + filterQuery);
        }
        //[TestMethod]
        public void TestGetWeb()
        {
            SPOHttpClient spoClient = new SPOHttpClient(login, password, site);
            Web           web       = spoClient.GetData <Web>("/_api/web");

            Assert.AreEqual("Dev", web.Title);

            ListItem item = spoClient.GetData <ListItem>("/_api/web/lists/getByTitle('Umowy')/items(1)");

            item.Title    = "Test updated!";
            item.Metadata = new Metadata()
            {
                Type = "SP.Data.UmowyListItem"
            };
            Dictionary <string, string> headers = new Dictionary <string, string>()
            {
                { "IF-MATCH", "*" },
                { "X-HTTP-Method", "MERGE" }
            };
            dynamic response = spoClient.PostData <dynamic, ListItem>("/_api/web/lists/getByTitle('Umowy')/items(1)", item, headers);
        }