public void GetNextWords()
        {
            var allList = new List<Word>()
            {
                new Word() { ID = guids[0], Language = Language.En, UsingFrequencyNumber = 1 },
                new Word() { ID = guids[1], Language = Language.En },
                new Word() { ID = guids[2], Language = Language.En },
                new Word() { ID = guids[3], Language = Language.En },
                new Word() { ID = guids[4], Language = Language.En, UsingFrequencyNumber = 2 }
            };
            var resList = new List<WordResult>()
            {
                new WordResult() { Word = new Word() { ID = guids[3], Language = Language.En } },
                new WordResult() { Word = new Word() { ID = guids[4], Language = Language.En } },
            };

            var wordResultStorage = new Mock<IStorage<WordResult>>();
            wordResultStorage.Setup(s => s.AllList).Returns(() => resList);

            var wordStorage = new Mock<IWordStorage>();
            wordStorage.Setup(s => s.GetWordsByLanguage(It.Is<Language>(x => x == Language.En))).Returns(() => allList);

            var provider = new WordSessionProvider(wordStorage.Object, wordResultStorage.Object, 5, 50);

            var actual = provider.GetNextWords(Language.En).ToArray();

            Assert.AreEqual(3, actual.Count());
            Assert.AreEqual(guids[0], actual[0].ID);
            Assert.AreEqual(guids[1], actual[1].ID);
            Assert.AreEqual(guids[2], actual[2].ID);
        }