Since functions are values you can just do that:
var NewExternalService func()Service = pkg.NewExternalService
and then mock NewExternalService
or explicitely inject dependencies in your http.HandlerFunc
func(Service) http.HandlerFunc{
return func(w http.ResponseWriter, r *http.Request){
// use Service here
}
}
or use http.Handler
type HandleLogin struct {
Service
}
func(h handleLogin)ServeHTTP(w http.ResponseWriter,r *http.Request){
h.Service.CallThis(r)
}
You can only write unit tests if you write testable code at first place.
Le mercredi 15 novembre 2017 03:28:28 UTC+1, Glen Huang a écrit :
>
> I find that to be able to unit test things in golang, I need to
> restructure them in an uncomfortable way in order to be able to mock their
> dependencies.
>
> For example, say I want to test this simple http handler:
>
> func handleLogIn(w http.ResponseWriter, r *http.Request) {
> svc := pkg.NewExternalService()
> value1 := parseValue1(r)
> svc.CallThis(value1)
> value2 := parseValue2(r)
> svc.CallThat(value2)
> }
>
> I want to mock pkg.NewExternalService, then use httptest to make sure
> given a http.Request, svc will be called with the correctly values.
>
> Right now, the solution I can come up with:
>
> 1. create a closure to create the service instead:
>
> var newExternalService = func () Service {
> return pkg.NewExternalService()
> }
>
> 2. override it in test:
>
> newExternalService = func () Service {
> return &MockService{}
> }
>
> Notice how I'm forced to use a closure instead of a function declaration.
>
> And then I have to turn Service into an interface so I can return a mock
> in test. But that's not the end of it. If I ever need to access a field of
> Service, I'm screwed, because interfaces can't contain fields. So I also
> have to restructure Service to expose fields as methods.
>
> I feel catering to the ability to be tested has too big an impact on my
> original code, and if I have no control over the design for the original
> Service, it seems it will be very difficult to test to say the least.
>
> I wonder if there is a better solution?
>
> Regards,
> Glen
>
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