How to enable all optional dependencies for tests

Help/Discuss
1

I have a complex Gradle project with some sub-projects having optional dependencies which are normally not used; I guess this can be modeled by features/capabilities. Among this sub-projects there is a ‘main’ sub-project which has dependencies on other sub-projects. This ‘main’ sub-project has test code which needs optional dependencies to be present in runtime.

How can I enable optional dependencies for ALL sub-projects used in ‘main’, but only for test code? Preferably without copy/pasting all ‘main’ dependencies twice - once for main code and one more time for test code with enabled capability.

2

I’m not sure exactly what you’re doing but I think you can do this via an additional configuration in the subprojects.

Eg:

project(':sub') {
   configurations {
      optional
   }
   dependencies {
      compile 'foo:required:1.0' 
      optional 'foo:optional:1.0'
   }
} 
project(':main') {
   dependencies {
      compile project(':sub') 
      testRuntime project(path: ':sub', configuration: 'optional') 
   } 
}

See DependencyHandler docs

By default, when you declare dependency to projectA, you actually declare dependency to the ‘default’ configuration of the projectA. If you need to depend on a specific configuration of projectA, use map notation for projects: configurationName project(path: ':projectA', configuration: 'someOtherConfiguration')

3

Yes, your code does what I want, but it does not scale well to larger project. For example:

subprojects {
   apply plugin: 'java-library'

   configurations {
      optional
   }
}
project(':sub1') {
   dependencies {
      optional 'org.postgresql:postgresql:42.2.9'
   }
} 
project(':sub2') {
   dependencies {
      implementation project(':sub1')
   }
} 
project(':sub3') {
   dependencies {
      optional 'commons-lang:commons-lang:2.4'
   }
} 
project(':sub4') {
   dependencies {
      implementation project(':sub3')
   }
} 
project(':main') {
   dependencies {
      implementation project(':sub2')
      implementation project(':sub4')
      // ???
   } 
}
4

You’ll need to break it down for me what you want to achieve and what you mean by “it doesn’t scale”

5

I. Transitive dependencies do not work “out of the box” - in my example ‘:main’ depends on ‘:sub2’, which depends on ‘:sub1’, which has an optional dependency. If I simply add

testRuntime project(path: ':sub2', configuration: 'optional')

then optional dependencies from ‘:sub1’ won’t be present.

II. In the example ‘:main’ depends on both ‘:sub2’ and ‘:sub4’, and I don’t want to repeat all these dependencies for testRuntime with optional configuration (and in a real project there are many dependencies). I want some simple switch to enable all optional dependencies at once.

6

You’d need to join the optional configurations too.
Eg

project(':sub1') {
   dependencies {
      optional 'org.postgresql:postgresql:42.2.9'
   }
} 
project(':sub2') {
   dependencies {
      implementation project(':sub1')
      optional project(path: ':sub1', configuration:'optional') 
   }
} 
project(':main') {
   dependencies {
      implementation project(':sub2')
      testRuntime project(path: ':sub2', configuration:'optional') 
   } 
}
7

Unfortunately my project has more than 100 sub-projects, so it’s quite inconvenient to rewrite all these gradle files this way.

Since Gradle is highly programmable, there should be some trick to do it automatically.

8

You could probably do it via

subprojects {
   apply plugin: 'java-library'

   configurations {
      optional
   }
   configurations.implementation.incoming.dependencies.all {
      if (it instanceof ProjectDependency) {
          // wire the optional configurations together 
      } 
   } 
}
9

I solved my problem using plugins, variants and dependency substitution:

It’s not the simplest solution, but leaves declarative parts (build.gradles) quite clear, and works transparently for any transitive dependency depth.