public async Task GetOneSalary_ShouldReturnNull_IfNoMatch() { await dbContext.Salaries.AddAsync(new Salary { SalaryId = 1, Value = 100, TimePeriod = "some", EmployeeId = 1 }); await dbContext.Salaries.AddAsync(new Salary { SalaryId = 2, Value = 200, TimePeriod = "some2", EmployeeId = 1 }); await dbContext.Salaries.AddAsync(new Salary { SalaryId = 3, Value = 300, TimePeriod = "some2", EmployeeId = 2 }); await dbContext.SaveChangesAsync(); var dao = new PostgresDataAccessObjectService(dbContext); var obj = dao.GetOneSalary(11); Assert.Null(obj); }