How to unmarshal a reflect.Value in Golang

I got this test

func (t *DeviceTests) CreatePublicDevice() {
    registerRegularDevice := tester.TableTest{
        Method:      "POST",
        Path:        "/iot/devices",
        Status:      http.StatusOK,
        Name:        "CreatePublicDevice",
        Description: "register Regular Device has to return 200",
        Body:        PublicDevice,
    }
    resp := registerRegularDevice.DoubleSpin(t.Test)
    log.Println(resp.(types.Device).ID)

}

I want to keep this in a separate package so I can reuse on diferent projects.

func (test TableTest) DoubleSpin(t *testing.T) interface{} {
    actualBody := test.innnerSpin(t)
    log.Print(string(actualBody))
    thetype := reflect.TypeOf(test.Body)
    log.Println(thetype)
    receivedev := reflect.Zero(thetype)
    err := json.Unmarshal(actualBody, receivedev.Interface())
    assert.NoError(t, err)
    log.Println(receivedev)
    return receivedev.Interface()
}

Logs say:

2016/11/06 16:54:01 {"id":"581f7c49b2c79a543c627474","hostname":"Shriekersolar","alias":"my PublicDevice","channels":8,"owner":"public","location":{}}
2016/11/06 16:54:01 types.Device
2016/11/06 16:54:01 {ObjectIdHex("")   0  map[]}
2016/11/06 16:54:01 ObjectIdHex("")

Where a device looks like:

type Device struct {
    ID       bson.ObjectId     `json:"id" bson:"_id,omitempty"`
    Hostname string            `json:"hostname"`
    Alias    string            `json:"alias"`
    Channels int               `json:"channels"`
    Owner    string            `json:"owner"`
    Location map[string]string `json:"location"`
}