retail_test.go

import "errors"

type WarehouseMock struct {}

func(warehouse *WarehouseMock) GetProduct(id int) (Product, error){
  if id != 1 {
    return Product{}, errors.New("test")
  }
  return Product{}, nil
}

func(warehouse *WarehouseMock) InsertProduct(product Product) error{
  return nil
}

func TestRetail_GetMyProduct(t *testing.T) {
  retail := New(&WarehouseMock{})
  
  got, err := retail.GetMyProduct()
  if err != nil {
    t.Error("unit test failed, error expected nil")
  }
  empty := Product{}
  if got != empty {
    t.Error("unit test failed, product expected empty")
  }
}