title: Single column Date table issue:Groovy:Date variable '_' needs to be declared as method parameter
body: <p>I have a very simple test as blow:</p>
  
  <pre><code>def "setContent_activity_finished"(Status editStatus) {
      // Variables.........................
  
      given:
      activity.getStatus() &gt;&gt; editStatus.toString()
  
      when:
      handler.setContent(activityId,jsonString)
  
      then:
      0*view.appendPossible(_)
  
      where:
      editStatus       |_
      FINISHED         |_
      CANCELED         |_
  }
  </code></pre>
  
  <p>According to the document <a href="http://spock-framework.readthedocs.org/en/latest/data_driven_testing.html" rel="noreferrer">http://spock-framework.readthedocs.org/en/latest/data_driven_testing.html</a> 
  Data tables must have at least two columns. A single-column table can be written as:</p>
  
  <pre><code>where:
  a | _
  1 | _
  7 | _
  0 | _
  </code></pre>
  
  <p>And I follow this rule,but got an error look like picture shown:</p>
  
  <pre><code>Groovy:Date variable '_' needs to be declared as method parameter
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/OtxOX.png" alt="enter image description here"></p>
  
  <p>so,please tell me What the problem is here?</p>