cannot understand spock interaction - spock

Question

Here's a unit test that works fine.
#Subject([WeatherServiceImpl.class,URLConnection.class])
class WeatherServiceImplSpec extends Specification{
def "First spock test I ever wrote"(){
given: "some mock objects"
//1. define mock HttpURLConnection object
def mockConnObj=Mock(HttpURLConnection.class)
//2. defn of another mock
def mockURLAdaptor=Mock(URLAdapter)
when: "define some calls"
def test=new WeatherServiceImpl(mockURLAdaptor)
test.run("Raleigh")
then: "make some assertions"
1*mockURLAdaptor.openConnection(_)>>mockConnObj
1*mockConnObj.getResponseCode()
}//end def test
}
What I don't understand is that if I do this in the 'given' block:
def mockURLAdaptor = Mock(URLAdapter) >> {
​ openConnection(_) >> mockConnObj
}
then the method stub doesn't actually return the mock connection object as intended. To me, this is the more natural flow of expressions. Doing the same thing in the 'then' block, however, works as intended. Not sure what's going on here. Can't seem to find a relevant discussion on the web. I may also post this on stackoverflow.
Here's the class under test:
package com.icidigital.services.impl
import com.icidigital.Helpers.URLAdapter
import com.icidigital.services.IWeatherService
public class WeatherServiceImpl implements IWeatherService {
private URLAdapter urlAdapter;
private URLConnection urlConn;
public WeatherServiceImpl(URLAdapter urlAdapter){
//injecting this dependency, so I can unit test
//by injecting a mock URLAdapter instance. In
//normal operation, urlAdaptee would be an instance
//of URLWrapper, which simply wraps around the
// URL class, which is a final class and cannot
// be mocked normally.
this.urlAdapter=urlAdapter;
}
public String run(String city){
...
..
urlConn=urlAdapter.openConnection(city);
//(throws a null pointer exception while spock-ing)
urlConn.setRequestMethod("GET");
}
}
And here's the url adapter that exposes the method: openConnection. In the running code, there is a class URLWrapper that simply wraps around the java.net.URL class. I needed to do this to get around the fact that I couldn't directly mock the java.net.URL class since it is a final class.
interface URLAdapter {
public HttpURLConnection openConnection(String cityName);
}

Answer 1

If you want to return some object you should use a Stub instead.
#Subject([WeatherServiceImpl.class,URLConnection.class])
class WeatherServiceImplSpec extends Specification{
def "First spock test I ever wrote"(){
given: "some mock objects"
//1. define mock HttpURLConnection object
def mockConnObj=Mock(HttpURLConnection.class)
//2. defn of another mock
def mockURLAdaptor=Stub(URLAdapter)
mockURLAdaptor.openConnection(_)>>mockConnObj
when: "define some calls"
def test=new WeatherServiceImpl(mockURLAdaptor)
test.run("Raleigh")
then: "make some assertions"
1*mockConnObj.getResponseCode()
}//end def test
}
You can do it with Mocks as well, I just tried this and it worked
def "First spock test I ever wrote"() {
given: "some mock objects"
//1. define mock HttpURLConnection object
def mockConnObj = Mock(HttpURLConnection.class)
//2. defn of another mock
def mockURLAdaptor = Mock(URLAdapter)
1 * mockURLAdaptor.openConnection(_) >> mockConnObj
when: "define some calls"
def test = new WeatherServiceImpl(mockURLAdaptor)
test.run("Raleigh")
then: "make some assertions"
1 * mockConnObj.getResponseCode()
}//end def test
Hope it helps!

Answer 2

The following work(s):
#Subject([WeatherServiceImpl.class,URLConnection.class])
class WeatherServiceImplSpec extends Specification{
def "First spock test I ever wrote"(){
given: "some mock objects"
//1. define mock HttpURLConnection object
def mockConnObj=Mock(HttpURLConnection.class)
//=========================================
//2. defn of another mock
// Either/Or:
//def mockURLAdaptor=Mock(URLAdapter)
def mockURLAdaptor=Stub(URLAdapter)
//followed by:
mockURLAdaptor.openConnection(_)>>mockConnObj
//OR
def mockURLAdaptor=Stub(URLAdapter){
openConnection(_)>>mockConn
}
//BUT NOT:
def mockURLAdaptor=Mock(URLAdapter){
openConnection(_)>>mockConn
}
//=========================================
when: "define some calls"
def test=new WeatherServiceImpl(mockURLAdaptor)
test.run("Raleigh")
then: "make some assertions"
1*mockConnObj.getResponseCode()
}//end def test
}