How to mock a method which passes in clazz? - unit-testing

Question

I'm trying to write a unit test for a method which has takes in a .class parameter.
For example:
ExampleService {
def myExample(clazz){
//do stuff and return some object
}
}
/* How the above function gets used */
AnotherExampleService extends exampleService {
def blah() {
def obj = myExample(AnotherClass.class)
}
}
/* Now I need to test the above blah() function */
AnotherExampleServiceSpec extends Specification {
def "test blah"() {
//The following doesn't seem to work
ExampleService.metaClass.myExample = { def arg1 -> obj }
}
}
I'm pretty new to Groovy/Grails, so any help would be much appreciated. I basically want to know why my unit test doesn't seem to work, and how to test such a function that takes in a paramter of a class instance.
Thank you for your help!

Answer 1

I would probably subclass the ExampleService in the test. So it looked like:
ExampleService {
def myExample(clazz){
//do stuff and return some object
}
}
AnotherExampleService extends ExampleService {
def exampleService
def blah() {
def obj = myExample(AnotherClass)
}
}
AnotherExampleServiceSpec extends Specification {
def "test blah"() {
given:
AnotherExampleService service = new AnotherExampleService() {
#Override
def myExample(clazz){
//whatever you want to do
return whatEverResult
}
when:
def result = service.blah (SomeClass)
then:
result
}
}
As you can see the myExample methods is overridden here to return some mock value and there's no tinkering with metaclass :-) To make it easier for Groovy you can explicitly state the input type e.g. def myExample(Class clazz).