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);
}