Unexpected method call with custom struct constant.

Start by reproducing the supplied MockedUserDao example against revision 4d4bfba8f1d1027c4fdbe371823030df51419987, comparing the configured providerID with the value in the failure. Then inspect testify/mock's argument-matching path and existing mock tests. Done means establishing whether the differing UUID values explain the failure or exposing a matching defect with a focused regression test.

I'm experiencing some strange behavior I think may be a bug. I have the following types.

package model

type IdentityProvider string

var IdentityProviderGoogle = "google"

var IdentityProviderOffice365 = "office365"

I then have the following mock interface and implementation

package dataaccess

//UserDao the service for working with Users
type UserDao interface {
        //GetByProviderID get the user by the provider id
	GetByProviderID(provider model.IdentityProvider, providerID string) (*model.User, error)
}


// MockedUserDao is a mocked object that implements an interface
// that describes an object that the code I am testing relies on.
type MockedUserDao struct {
	dataaccess.UserDao
	mock.Mock
}


//GetByProviderID get the the providerid
func (m *MockedUserDao) GetByProviderID(provider model.IdentityProvider, providerID string) (*model.User, error) {
	args := m.Called(provider, providerID)

	return nilSafeUser(args)
}

func nilSafeUser(args mock.Arguments) (*model.User, error) {

	user := args.Get(0)
	err := args.Error(1)

	if user == nil {
		return nil, err
	}

	return user.(*model.User), err
}

I then mock with the following call

userDao.On("GetByProviderID", model.IdentityProviderGoogle, "1c3a9049-2116-11e7-986e-acde48001122").Return(otherUserEmail, nil)

What I expect to happen:

My pointer to "otherUserEmail" to be returned

What actually happens. Mocking fails to return.

mock: Unexpected Method Call
-----------------------------

GetByProviderID(model.IdentityProvider,string)
		0: "google"
		1: "1c3a9040-2116-11e7-986e-acde48001122"

The closest call I have is:

GetByProviderID(model.IdentityProvider,string)
		0: "google"
		1: "1c3a9049-2116-11e7-986e-acde48001122"

I could be incorrect, but from my observation, the values appear to be the same memory in index 0, and the same string in index 1. I'm using revision 4d4bfba8f1d1027c4fdbe371823030df51419987 as my dependency via vendor directory.

Env: go version go1.7.4 darwin/amd64