title: Unit testing grails ConfigSlurper behavior
body: <p>I'd like to write tests that would test behavior of externalized configs and assert that what gets set is what I expect. This is for the specific case where something like this is done:</p>
  
  <p>Config.groovy:</p>
  
  <p>a.reused.value = 'orig'
  my.variable = '${a.reused.value}'</p>
  
  <p>Externalized groovy file:</p>
  
  <p>a.reused.value = 'new_value'</p>
  
  <p>I expect that both a.reused.value and my.variable would be 'new_value'.</p>
  
  <p>Now, I think I could have my unit test read in strings representing these config files (I do similar things for other unit tests to populate Holders.grailsApplication.config, for example), utilizing perhaps merge?</p>
  
  <p>But what I cannot figure out is how to get the value that Grails actually gets during application run time. Instead, I get "${a.reused.value}" in my unit tests.</p>
  
  <p>Is there a way to mimic this behavior of what Grails does of actually resolving this value? I did some digging around in Grails 2.4.4 source (which is what we are using) and didn't have any luck in figuring this part out. I also did try Eval.me(), but that doesn't seem to be quite right either.</p>