Grails spock- how to mock/stub a particular method of class - grails

Question

I am writing Junit testcases for a Grails project.
Here I am using Spock framework to write testcases.
Here I am trying to test following method.
But I want to mock/stub the rest.post method. I don't want call the actual url passed.
def RestResponse restPost(String url, Map headerMap, Map jsonDataMap) {
RestBuilder rest = new RestBuilder()
RestResponse response = rest.post(url) {
headerMap.each { k, v -> header(k, v) }
header('contentType', 'application/json')
header('Accept-API-Version', 'resource=2.0,protocol=1.0')
if (jsonDataMap)
json(jsonDataMap)
}
response
}
I tried with MockFor. It is calling actual url.
void "test restPost"() {
setup:
RestResponse resMock = new RestResponse()
def httpBuildMock = new MockFor(RestBuilder)
httpBuildMock.demand.post(_) >> resMock
when:
def url = "http://testme"
def headerMap = [
'Authorization': 'Basic ' + 'encodedStr'
]
def dataMap = [
'operation': 'replace',
'field' : 'userPassword',
'value' : 'devicePassword'
]
RestResponse res = service.restPost(url, headerMap, dataMap)
then:
res
}
So how to mock/stub a particular method of class?

Answer 1

You could create a seperate method to create the RestBuilder so createRestBuilder and then return a mock everytime this method is called:
def RestResponse restPost(String url, Map headerMap, Map jsonDataMap) {
RestBuilder rest = createRestBuilder()
RestResponse response = rest.post(url) {
headerMap.each { k, v -> header(k, v) }
header('contentType', 'application/json')
header('Accept-API-Version', 'resource=2.0,protocol=1.0')
if (jsonDataMap)
json(jsonDataMap)
}
response
}
then define service with
def service = Spy(ServiceClass) {
// stub a call on the same object
createRestBuilder() >> Mock(RestBuilder)
}