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I'm mocking out a DataStore and it's Get/Set functionality. The trouble I'm having is: cannot use s (type *MockStore) as type *datastore.Storage in argument to EventHandler

This is caused by my EventHandler function needing to be passed a *datastore.Storage as an argument type. I want to Test (http test) EvenHandler() using the MockStore I've created instead of the real datastore. I'm using the golang testify mock package.

Some Code Examples

type MockStore struct{
  mock.Mock
}

func (s *MockStore) Get() ... 

func EventHandler(w http.ResponseWriter, r *http.Request, bucket *datastore.Storage){
  //Does HTTP stuff and stores things in a data store
  // Need to mock out the data store get/sets
}

// Later in my Tests
ms := MockStore
EventHandler(w,r,ms)
Hacking Life
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1 Answers1

3

A few things:

  • Create an interface that will be implemented both by datastore.Storage and your mock store.
  • Use the above interface as the argument type in EventHandler (not a pointer to the interface).
  • Pass a pointer to your MockStore to EventHandler, as the Get method is defined for a pointer to the struct.

Your updated code should be something like the following:

type Store interface {
   Get() (interface{}, bool) // change as needed
   Set(interface{}) bool
}

type MockStore struct {
   mock.Mock
}

func (s *MockStore) Get() ... 

func EventHandler(w http.ResponseWriter, r *http.Request,bucket datastore.Storage){
   //Does HTTP stuff and stores things in a data store
   // Need to mock out the data store get/sets
}


// Later in my Tests
ms := &MockStore{}
EventHandler(w,r,ms)
Community
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  • I've been working with this - but it doesn't seem to solve the core problem of EventHandler's argument "bucket" being of type datastore.Storage. In your line EventHandler(w,r,ms) ms is the MockStore struct. So the error: cannot use type MockStore as type datastore.Storage still exists. – Hacking Life Oct 24 '15 at 14:20
  • @HackingLife: I have just updated my answer; see if those changes help any. –  Oct 24 '15 at 15:18
  • This solves my problem. I was using a pointer to interface. Thanks :) – Marko Aug 21 '23 at 10:54