title: spock: need a hook to perform some setup steps before any test class executes
body: <p>I have several Spock test classes grouped together in a package. I am using Junit 4.10. Each test class contains several feature test methods. </p>
  
  <p>I want to perform some setup steps (such as loading data into a DB, starting up a web server) before I run any test case, but only once when the testing starts. </p>
  
  <p>I want this "OneTimeSetup" method to be called only once whether:</p>
  
  <ul>
  <li>I run all the test classes in the package (for example if they are grouped in a Test Suite)</li>
  <li>I run a few test classes</li>
  <li>I run only one test class</li>
  <li>I run only a certain feature method within a test class</li>
  </ul>
  
  <p>From reading other posts on SO, it seems that this is what TestNG's @BeforeSuite does.</p>
  
  <p>I am aware of Spock's setupSpec() and cleanupSpec() methods, but they only work within a given test class. I am looking to do something like "setupTestSuite()." How can this be achieved in Spock?</p>