Model in Grails Controller Tests is Null/Empty

Question

I recently created a new controller in a pretty big app, (note: we just upgraded from Grails 2.0.3 to 2.3.7) and the created tests have all been failing inexplicably. Most of my errors consist of the model being [:] after a controller call. And therefore any methods on that model being null. I get stuff like:

groovy.lang.MissingMethodException: 
No signature of method: 
TransitionController.save() is applicable for argument types: (Transition) 
values: [null] Possible solutions: save(), wait(), show(), any(), 
wait(long), raw(java.lang.Object) at TransitionControllerSpec.Test the 
save action correctly persists an instance(TransitionControllerSpec.groovy:45)

I have tried explicitly assigning the model by doing:

def model = controller.delete()
def model = controller.update()
//....

But I get the same result, an empty model map and null values if I try to access it. As per this article (https://jira.grails.org/browse/GRAILS-8462) I could also try accessing the model by doing:

def model = controller.modelAndView.model 

But this did not work for me either, producing the same results.

Any ideas on what might be happening?

Edit: Here are the first couple of tests

package com.hey.how.are.ya

import grails.test.mixin.*
import spock.lang.*
import org.junit.*

@TestFor(TransitionController)
@Mock(Transition)
class TransitionControllerSpec extends Specification {

def populateValidParams(params) {
    assert params != null
    params['reason'] = 'just cuz'
}

void "Test the index action returns the correct model"() {

    when:"The index action is executed"
        controller.index()

    then:"The model is correct"
        !model.transitionInstanceList
        model.transitionInstanceCount == 0
}

void "Test the create action returns the correct model"() {
    when:"The create action is executed"
        controller.create()

    then:"The model is correctly created"
        model.transitionInstance!= null
}
//...grails generated tests here

}

Edit: Here's an interesting case! If I do:

void "Test the create action returns the correct model"() {
    when:"The create action is executed"
        def model = controller.create()
        def inst = new Transition()
        println "${model}"
        println "${model.transitionInstance}"
    then:"The model is correctly created"
        model.transitionInstance != null
}

Then I get this as output:

[transitionInstance:null]
null

But the test passes. This only happens with create. What is going on??

Edit: Adding code for create and save

def create() {
    [transitionInstance: new Transition(params)]
}

def save() {
    def transitionInstance = new Transition(params)
    if (!transitionInstance.save(flush: true)) {
        render(view: "create", model: transitionInstance: transitionInstance])
        return
    }

    flash.message = message(code: 'default.created.message', args: [message(code: 'transition.label', default: 'Transition'), transitionInstance.id])
    redirect(action: "show", id: transitionInstance.id)
}

Edit: I can't spend too much time on this, but I'm pretty sure the problem is discrepancies between the controller generated and the test created. For what it's worth I was running version 2.0.2 of the scaffolding plugin and grails 2.3.7. I'm gonna throw out the tests created by the command and start from scratch, thanks for the help!

Answer 1

I had the same issue but solved it like following:

Inside the controller method:

 render view: "_myTemplate", model: [instance: myInstance]

So the controller, still renders the template and inside the test spec I can test

assert(model.instance = myExpectedInstance)