Grails gradle "a task with that name already exists"

Question

I'm trying to create a test task rule using the example provided in the grails gradle doc but I keep getting "a task with that name already exists" error.

My build script is as follows:

import org.grails.gradle.plugin.tasks.* //Added import here else fails with "Could not find property GrailsTestTask"

buildscript {
  repositories {
    jcenter()
  }
  dependencies {
    classpath "org.grails:grails-gradle-plugin:2.0.0"
  }
}

version "0.1"
group "example"

apply plugin: "grails"

repositories {
  grails.central() //creates a maven repo for the Grails Central repository (Core libraries and plugins)
}

grails {
  grailsVersion = '2.3.5'
  groovyVersion = '2.1.9'
  springLoadedVersion '1.1.3'
}

dependencies {
  bootstrap "org.grails.plugins:tomcat:7.0.50" // No container is deployed by default, so add this
  compile 'org.grails.plugins:resources:1.2' // Just an example of adding a Grails plugin
}

project.tasks.addRule('Pattern: grails-test-app-<phase>') { String taskName ->
    println tasks //shows grails-test-app-xxxxx task. Why?
    //if (taskName.startsWith('grails-test-app') && taskName != 'grails-test-app') {
    //    task(taskName, type: GrailsTestTask) {
    //        String testPhase = (taskName - 'grails-test-app').toLowerCase()
    //        phases = [testPhase]
    //    }
    //}
}

Running $gradle grails-test-integration or in fact anything of the form $gradle grails-test-app-xxxxxxxx yields the error "Cannot add task 'gradle grails-test-app-xxxxxxxx as a task with that name already exists".

Can someone please advise how I can resolve this error? Thanks.

Powers

Have you tried with a different task name pattern? Have you tried to check for existence of a task before adding it? – Kleper

Hi Peter, yes I've tried different patterns it always fails with the error "Cannot add task... a task with that name already exists." – Powers

Strange. Chances are the problem is somehow connected to the grails-gradle-plugin (which I'm not familiar with). – Kleper

My best guess is that the grails-gradle-plugin itself adds a "catch all" task rule that delegates to the Grails build system. In that case, you may not be able to declare your own task rules when using this plugin. – Kleper

@PeterNiederwieser: I think you are right. Looking through the plugin's source code, there is an addRule that creates tasks for patterns prefixed with 'grails-'. Is there a way I can create a task of the same pattern that precedes the plugin? I.e. in build.gradle how do I create a task of the form grails-XXX before the plugin does? Or is that ill-advised? – Powers

You could try to add your own pattern before applying the grails plugin. Or you use a different pattern. – Kleper

@PeterNiederwieser: Thanks. Creating my custom rule before applying the plugin did not work since the plugin will try to create the same rule. Like you mentioned, I'll probably have to use a different pattern. Thanks once again for your help. – Powers

@PeterNiederwieser: I think there is an issue with addRule. I commented out the contents of the addRule block and replaced it with println tasks (pls see edited post above). The task with pattern grails-XXXX gets created with just the call to addRule. If addRule is removed, the task is never created. Somehow addRule is creating the task even though i do not explicitly call tasks.create in my build script. – Powers

Try w/o applying the Grails plugin. It's more likely something about that plugin. – Kleper

@PeterNiederwieser: I would like to debug this issue. Can you please advise how I can trace the addRule calls? Seems like the addRule was overriden in the plugin. Can it be overriden? – Powers

Answer 1

If you don't mind overriding the task created by the plugin, you might want to try

task(taskName, type: GrailsTestTask, overwrite: true)

In general, when using task rules that can be called multiple times (for instance if you have multiple tasks depending on a task eventually added by your rules), I use the following test before actually creating the task:

if (tasks.findByPath(taskName) == null) {tasks.create(taskName)}

This will call the task() constructor only if this task name does not exists.

Evita

What does it mean to "override a task"? Does it mean that the current execution of the task gets negated when another code calls it. – Palaeozoology

It means that you replace the task provided by the plugin with your task definition. The one that gets executed is yours. See the documentation for more details: docs.gradle.org/current/userguide/… – Evita