public void TestSetup()
        {
            var connectionStringBuilder = new SqliteConnectionStringBuilder {
                DataSource = ":memory:"
            };
            var connectionString = connectionStringBuilder.ToString();
            var connection       = new SqliteConnection(connectionString);

            var options = new DbContextOptionsBuilder <SchoolDbContext>()
                          .UseSqlite(connection)
                          .Options;

            _dbContext = new SchoolDbContext(options);
            _dbContext.Database.OpenConnection();
            _dbContext.Database.EnsureCreated();
            _dbContext.EnsureSeeded();

            _testController = new ClassesController(_dbContext);
        }