Gretty version 1.1.5+ allows to override context path in integration test tasks. This can be useful, when you need to run integration tests against "alien" web-app, coming in form of WAR-file. Example:

apply plugin: 'org.akhikhl.gretty'

test {
  include '**/Test*.*'
  include '**/*Test.*'
  exclude '**/*IT.*'

task integrationTest(type: Test, dependsOn: 'test') {
  outputs.upToDateWhen { false }
  include '**/*IT.*'
  // we explain to integrationTest that contextPath under test is "helloGretty", not this project
  ext.contextPath = 'helloGretty'

farm {
  // we serve helloGretty.war under http://localhost:8080/helloGretty
  webapp 'helloGretty.war'
  // we run integration tests of this project
  webapp project

  // this is needed only if WAR-file is generated in the same project tree
  // afterEvaluate {
  //   project.tasks.farmBeforeIntegrationTest.dependsOn ':helloGretty:build'
  // }

With such setup just invoke gradle farmIntegrationTest to run integration tests.

The complete working example of overriding context path in integration test tasks is available here: