Unit Testing nested command objects in grails - unit-testing

Question

Docs say we can test controllers with command objects just by mocking params
http://grails.org/doc/latest/guide/testing.html#unitTestingControllers
I wonder if this works for Nested Command Objects? Has anyone gotten this to work?
Example:
Controller
def create(FormCommand form){
form.validate()
...
}
Command
class FormCommand {
InnerCommand cmd
}
class InnerCommand{
String x
static constraints ={
x(nullable: false)
}
}
Test
void testCreate(){
params["inner.x"]="any"
controller.create()
...
}
My expectation is that the command objects are created and data binding works, also I expect inner command to be validated. Am I expecting too much?

Answer 1

Ok, it seems that's possible what you want, but needs some code :-)
Data Binding
For nested command objects Grails databinding needs a not null instance of the inner command.
To do that, you can create a custom org.codehaus.groovy.grails.web.binding.BindEventListener:
class InnerCommandBindEventListener împlements BindEventListener {
public void doBind(Object target, MutablePropertyValues source, TypeConverter typeConverter) {
target.cmd = new InnerCommand()
}
}
And declare it in your resources.groovy
innerCommandBindEventListener(InnerCommandBindEventListener)
Nested Validation
To resolve the validation issue, you need a custom validator for your cmd:
class FormCommand {
InnerCommand cmd
static constraints = {
cmd nullable: false, validator: { cmd, obj ->
// manually trigger the inner command validation
if(!cmd.validate()) {
return 'invalid.innercommand.message'
}
}
}
}

Answer 2

Not sure if exactly applicable to the issue at hand, but for at least the data binding in tests for controller actions this works:
params.'player1.name' = "John"
Where as this gives null pointer exception:
params.player1.name = "John"
When controller is doing:
Game game = new Game(params)
And Game has:
Player player1