Set the Locale of your integration test

MyTestSpec.groovy

import grails.plugin.spock.IntegrationSpec

import org.springframework.web.context.request.RequestContextHolder

class MyTestSpec extends IntegrationSpec {

  /* Normally in your code you will use something like RequestContextUtils.getLocale(request) to get's the Locale to
   * be used. Here we set the locale that will be returned by RCU to our tests.
   */
  def setup() {
    //get's the instance of the mock
    def request = RequestContextHolder.currentRequestAttributes().request
    //and then set your locale
    request.addPreferredLocale(new Locale("pt","BR"))
  }
}