How to set an environment variable from a Gradle build?

I'm trying to set an environment variable from my Gradle build. I'm on MacOS X (El Capitan). The command is "gradle test".

I'm trying this in my build.gradle:

task setenv(type: Exec) {
    commandLine "export", "SOME_TEST_VAR=aaa"
}
test.dependsOn setenv

and the build fails:

Execution failed for task ':myproject:setenv'.

A problem occurred starting process 'command 'export''

I also tried this:

test.doFirst {
    ProcessBuilder pb1 = new ProcessBuilder("export SOME_TEST_VAR=some test value")
    pb1.start();
}

The build succeeds. However, if I check the environment variable in my JUnit test it fails:

assertTrue(System.getenv().containsKey("SOME_TEST_VAR"));

Is there any way to set an environment variable from a Gradle build (in the build.gradle file)?

Update:

I've tested it in isolation: the values do get passed and my test task receives everything, be it a systemProperty, environment variables or jvmArgs.

So, it's nothing wrong with Gradle itself here.

The problem arises when I'm trying it on the real project. It uses Spring for dependency injection. I may be wrong but it looks like the Spring framework purges those values somewhere.

That sub-project is currently being frozen and I can't check my guess in detail right now.

For a test task, you can use the environment property like this:

test {
  environment "VAR", "val"
}

you can also use the environment property in an exec task

task dropDatabase(type: Exec) {
    environment "VAR", "val"
    commandLine "doit"
}

Note that with this method the environment variables are set only during the task.

You can also "prepend" the environment variable setting by using 'environment' command:

run.doFirst { environment 'SPARK_LOCAL_IP', 'localhost' }

If you have global environment variables defined outside Gradle,

test {
    environment "ENV_VAR",  System.getenv('ENV_VAR')
    useJUnitPlatform()
}