ratpackSimpleAsyncPromise.groovy

import ratpack.exec.Promise
import ratpack.handling.Context
import ratpack.groovy.test.embed.GroovyEmbeddedApp

@GrabResolver(name = 'jcenter', root = 'http://jcenter.bintray.com/')
@GrabExclude('org.codehaus.groovy:groovy-all')
@Grab('org.slf4j:slf4j-simple:1.7.12')

@Grab('io.ratpack:ratpack-groovy:1.3.3')
@Grab('io.ratpack:ratpack-rx:1.3.3')
@Grab('io.ratpack:ratpack-groovy-test:1.3.3')

GroovyEmbeddedApp app = GroovyEmbeddedApp.of {
  handlers {
    all { Context context ->

      println "A. Original compute thread: ${Thread.currentThread().name}"

      Promise.async { downstream ->
        println "B. Promise thread : ${Thread.currentThread().name}"
        downstream.success("hello from async promise")
      }.then { result ->
        context.render result
      }

      println "C. Original compute thread: ${Thread.currentThread().name}"
    }
  }
}.test {
    assert getText() == "hello from async promise"
}