public void getAllRows()
        {
            Dictionary <string, string> expectedRows = new Dictionary <string, string>
            {
                ["1"] = "test value1",
                ["2"] = "test value2",
                ["3"] = "test value3",
                ["4"] = null
            };

            foreach (var row in expectedRows)
            {
                storage[row.Key] = row.Value;
            }

            Assert.AreEqual(
                expectedRows,
                storage.ToDictionary(row => row.Key, row => row.Value)
                );
        }
 public Dictionary <string, string> GetAll()
 {
     return(_storage.ToDictionary(row => row.Key, row => row.Value));
 }