Determine if a task is defined in an external build.gradle file - gradle

Question

I have a gradle task that is created at runtime to call another task ("myOtherTask") which is in a separate gradle file. The problem is if that other task doesn't exist an exception will be thrown. Is it possible to check that a task exists in an external gradle file before attempting to call it?
Example:
task mainTaskBlah(dependsOn: ':setupThings')
task setupThings(){
//...
createMyOtherTask(/*...*/)
//...
}
def createMyOtherTask(projName, appGradleDir) {
def taskName = projName + 'blahTest'
task "$taskName"(type: GradleBuild) {
buildFile = appGradleDir + '/build.gradle'
dir = appGradleDir
tasks = ['myOtherTask']
}
mainTaskBlah.dependsOn "$taskName"
}

Answer 1

You can check if the tasks exists. For example if we wanted to simulate this we could make the task creation triggered by a command line property
apply plugin: "groovy"
group = 'com.jbirdvegas.q41227870'
version = '0.1'
repositories {
jcenter()
}
dependencies {
compile localGroovy()
}
// if user supplied our parameter (superman) then add the task
// simulates if the project has or doesn't have the task
if (project.hasProperty('superman')) {
// create task like normal
project.tasks.create('superman', GradleBuild) {
println "SUPERMAN!!!!"
buildFile = project.projectDir.absolutePath + '/build.gradle'
dir = project.projectDir.absolutePath
tasks = ['myOtherTask']
}
}
// check if the task we are interested in exists on the current project
if (project.tasks.findByName('superman')) {
// task superman exists here we do whatever work we need to do
// when the task is present
def supermanTask = project.tasks.findByName('superman')
project.tasks.findByName('classes').dependsOn supermanTask
} else {
// here we do the work needed if the task is missing
println "Superman not yet added"
}
Then we can see both uses cases rather easily
$ ./gradlew -q build -Psuperman
SUPERMAN!!!!
$ ./gradlew -q build
Superman not yet added

Answer 2

This won't help you find if the task is in a specific external file, but if you just want to determine if a task is defined in any of your imported gradle files...
From gradlew help I see there is a tasks task.
Sadly, gradlew tasks doesn't always show all taks. Some of my projects have an integrationTest task while others do not, in which case I can only go as far as build. However, the default tasks command lists integrationTestClasses but not integrationTest.
From gradlew help --task tasks I can see there is a report expanding --all parameter that we can use.
Now, I can see all tasks via gradlew tasks --all, so a simple grep can tell me whether or not the task I want exists. In bash, this might look like:
TASK="integrationTest"
if gradlew tasks --all | grep -qw "^$TASK"
then
gradlew clean integrationTest
else
gradlew clean build
fi
FYI --
Personally, I needed something to tell me in a git pre-commit hook whether the integrationTest task existed or not, so I know whether I can run gradlew integrationTest or if I have to stop at gradlew build. Not finding an answer here, I kept looking, and this is what I came up with to solve my problem. Hopefully, this is of use to others as well.

Answer 3

I made a little "tool" for stuff like that - maybe it comes in handy for some of you...
$ cat if_gradle_task_exists
#!/bin/sh
TASKS=$(./gradlew tasks --all)
BUILD="./gradlew "
for COMMAND in $#; do
echo "$TASKS" | grep -q "$COMMAND" && BUILD="$BUILD $COMMAND"
done
$BUILD
You can append as many tasks as you like and only the existing ones are executed.
I use it in combination with alias as a kind of super api wrapper for tasks I want to be done in different projects (and I don't want to have to care if any of the specific tasks really do exist):
alias ge='~/.config/bin/if_gradle_task_exists eclipse initDb createTestUsers startLdapServerMock startBrokerMock'
That allows me to be as lazy as ge
stumpf#HV000408:/c/devel/workspace/myproject $> ge
to set up the project for eclipse and prepare all needed servers for local development.
The list of tasks produced will need some time to be set-up, so I wouldn't recommend to use it as a full gradlew wrapper though.
Regards