public async Task GetAllTest()
{
var purchases = new List <Purchase>();
purchases.Add(purchase);
IEnumerable <Purchase> purchaseList = purchases;
purchaseService.Setup(t => t.GetPurchases()).Returns(Task.Run(() => purchaseList));
var result = await purchaseController.GetAll(purchaseService.Object);
Assert.That(result, Is.InstanceOf <IActionResult>());
var ok = result;
Assert.That(ok, Is.Not.Null);
}