title: Spock "where" with dependent variables
body: <p>I am trying to do some data driven testing in Spock.</p>
  
  <p>I have 1 variable which depends on an other one : ie</p>
  
  <pre><code>Services = ["tf1", "fr2"]
  Questions(service) = ["What is on {service} ?", "Switch to {service}"]
  </code></pre>
  
  <p>I want my test to check all the possible combinations of Services and Questions(Service) : a total of 4 tests.</p>
  
  <p>I tried writing a <code>where:</code> clause like that :</p>
  
  <pre><code>    where:
        service &lt;&lt; SERVICES
        question &lt;&lt; Questions(service)
  </code></pre>
  
  <p>But that fails at runtime with a <code>groovy.lang.MissingPropertyException: No such property: service for class: com.my.testclass</code></p>
  
  <p>Has someone found a solution to this problem ?</p>