Mill Build Tool: How to run the tests of all Modules at once?

Question

I'm using Mill and I can't figure out how to run the tests or even compile all Modules at once.

There is clear, but running mill resolve _ does not seem to have a command for it.

For now I run the tests for each Module separately.

Is there a way to achieve this?

Answer 1

Edit: The Answer targets an outdated Mill version. See below for an updated version.

I assume you're talking about ScalaModules and your tests are located in test sub-modules.

Run all tests of your project with:

mill __.test.test

The __ is a wildcard and matches in this case any parent module(s) (like the ** in Ant patterns). The .test.test matches a test target in a module named test.

To compile all modules, run:

mill __.compile

And to run all compile targets and run tests in one go, run:

mill all __.compile __.test.test

Notice, that we need to use the all target here, which accepts multiple targets as arguments. That's needed because mill only accepts a single target or target-pattern and treats any additional command line argument as a parameter for that target.

Edit:

Newer versions of Mill no longer have the all command. Instead, you can give multiple targets separated with +.

mill __.compile + __.test

Also, to run all test targets, it's enough to run mill __.test. In very older Mill versions, this results in tests running twice, but this is fixed for a long time and the workaround to use __.test.test is no longer needed.