public async Task DisplayAllManager()
        {
            var context       = CreateContextForSQLite();
            var testManagerDb = GetTestManager(context);
            var controller    = new ManagersController(testManagerDb);
            var managerIds    = testManagerDb.Managers.Select(m => m.ManagerId).Distinct().ToList();
            var expected      = (await testManagerDb.Employees.ToListAsync())
                                .Where(e => managerIds.Contains(e.Id))
                                .ToList();
            var result = await controller.GetAllManagers();

            Assert.Equal(expected, result.Value);
        }