public void Count()
        {
            // Arrange
            SubjectRepository subjectRepository = new SubjectRepository(dbContext);
            int expectedSubjectInDb             = dbContext.Subjects.Count();

            // Act
            int actualSubjectInDb = subjectRepository.Count();

            // Assert
            Assert.AreEqual(expectedSubjectInDb, actualSubjectInDb);
        }
        public void CountIf4Messages()
        {
            // Arrange
            SubjectRepository subjectRepository = new SubjectRepository(dbContext);
            int numberOfMessagesperSubject      = 4;
            int expectedSubjectWithMessagesInDb = Resources.Classes.DbFiller.Instance.SubjectMessageAmount
                                                  .Count(s => s.Value == numberOfMessagesperSubject);

            // Act
            int actualSubjectWith4Messages = subjectRepository
                                             .Count(subject => subject.Messages.Count == numberOfMessagesperSubject);

            // Assert
            Assert.AreEqual(expectedSubjectWithMessagesInDb, actualSubjectWith4Messages);
        }