Unit testing a GORM call with a closure - unit-testing

Question

I have a Grails service that does a where query like this:
List<Car> search(Long makeId = null) {
Car.where {
join("make")
if(makeId) {
make.id == makeId
}
}.findAll()
}
I'm trying to unit test it with Spock like this:
def setup() {
GroovyMock(Car, global: true)
}
void "test search"() {
when:
service.search()
then:
1 * Car.where {}
}
However, I can't seem to find a way to test the content of the closure.
I can get the test to pass by verifying 1 * Car.where(_), but how can I make assertions on the content of the closure, i.e. that join was called and that the make.id constraint is specified only when needed?

Answer 1

You could set the closure's delegate to be an Mock of DetachedCriteria to make assertions on it. DetachedCriteria is the main class used in gorm to build the query.
Example:
given: 'Mocking DetachedCriteria'
DetachedCriteria detachedCriteriaMock = Mock(DetachedCriteria)
and: 'Just to avoid nullPointerException when findAll() call happens on service'
1 * detachedCriteriaMock.iterator() >> [].listIterator()
when:
service.search(1L)
then:
// Capture the argument
1 * Car.where(_) >> { args ->
args[0].delegate = detachedCriteriaMock
args[0].call()
return detachedCriteriaMock
}
// Join is a method on detached criteria
1 * detachedCriteriaMock.join('make')
// Make is an association, so detachedCriteria uses the methodMissing to find the property.
// In this case, we call the closure setting the delegate to the mock
1 * detachedCriteriaMock.methodMissing('make', _) >> { args ->
// args[1] is the list of arguments.
// args[1][0] is the closure itself passed to detachedCriteria
args[1][0].delegate = detachedCriteriaMock
args[1][0].call()
}
// If id is passed, it must compare (eq method) with value 1
1 * detachedCriteriaMock.eq('id', 1L)