How to set a dependency for a project with all subprojects?

Question

I don't like that I repeat every repository dependency (let us say, junit), for the main project and for subprojects. Is there a possibility to make the subproject to use the dependencies of the main project. Or is there another way to escape that repetition?

Answer 1

Unlike the accepted answer it's better to use the following:

allprojects {
  plugins.withType(JavaPlugin) {
    dependencies {
      testCompile 'junit:junit:4.12'
    }
  }
}

The changes will be applied immediately if java plugin already exists or will watch for it to be added and apply later.

Updated

At the moment I use better way to control configuration for plugin - pluginManager. The effect is the same as for plugins.withType, but you don't have to know plugin's class name:

Example for org.springframework.boot plugin:

apply plugin: 'org.springframework.boot'

allprojects {
  pluginManager.withPlugin('org.springframework.boot') {
    springBoot {
      buildInfo()
      layout 'DIR'
    }
  }
}

Answer 2

root/build.gradle

allprojects {
    if (plugins.hasPlugin('java')) {
        dependencies {
            testCompile 'junit:junit:4.12'
        }
    }
}