Unit Testing Go Functions having ORM interactions - unit-testing

Question

I have written a function:
func AllItems(w http.ResponseWriter, r *http.Request) {
db, err := gorm.Open("sqlite3", "test.db")
if err != nil {
panic("failed to connect database")
}
defer db.Close()
var items [] Item
db.Find(&items)
fmt.Println("{}", items)
json.NewEncoder(w).Encode(items)
}
I want to do unit testing on this. Ideally, unit testing means that each line of the function needs to be tested. I'm not sure how I should test if a database connection is opened and then if it is displaying all the contents of the database. How should I test this code?
This function is the GET endpoint of a simple CRUD application. The code is here.

Answer 1

Refactor your code and break it down into smaller, testable functions which you pass dependencies to. Also create interfaces for the dependencies to make testing easier.
For example:
type myDatabaseInterface interface {
Find(interface{}) // this signature should match the real db.Find()
}
func AllItems(w http.ResponseWriter, r *http.Request) {
db, err := gorm.Open("sqlite3", "test.db")
if err != nil {
panic("failed to connect database")
}
defer db.Close()
items := findItems(db)
json.NewEncoder(w).Encode(items)
}
func find(db myDatabaseInterface) ([]Item) {
var items []Item
db.Find(&items)
return items
}
Then you can create mocks for your dependencies and use them in your tests:
type mock struct {}
// mock should implement myDatabaseInterface to be able to pass it to the function
func (m *mock) Find(interface{}) {
// implement the mock to satisfy your test
}
func Test_find(t *testing.T) {
m := mock{}
res := find(m)
// do testing
}
Instead of calling Open every time you handle a request maybe you should open it outside and have it available to your function. That way the handler becomes so small there's no need to test it really:
func makeAllItemsHandler(db myDatabaseInterface) func(http.ResponseWriter, *http.Request) {
return func(http.ResponseWriter, *http.Request) {
items := findItems(db)
json.NewEncoder(w).Encode(items)
}
}
Then you can create a db once and for all when you set up your application and pass it to the functions that need it thus removing hard to test code from the functions.