scala-cli-integration-tests

name	scala-cli-integration-tests
description	Add or run Scala CLI integration tests. Use when adding integration tests, debugging RunTests/CompileTests/etc., or working in modules/integration.

Integration tests (Scala CLI)

Location: modules/integration/. Tests invoke the CLI as an external process.

Run: ./mill -i integration.test.jvm (all). Filter: ./mill -i integration.test.jvm 'scala.cli.integration.RunTestsDefault.*' or by test name. Native: ./mill -i integration.test.native.

Always set CI=true when running integration tests, unless the user explicitly asks otherwise:

CI=true ./mill -i integration.test.jvm 'scala.cli.integration.RunTestsDefault.*'

This disables test parallelism, so the run mirrors how the tests behave on CI. It is slower, but the extra time is an acceptable trade-off for reproducible results.

Structure: *TestDefinitions.scala (abstract, holds test logic) → *TestsDefault, *Tests213, etc. (concrete, Scala version trait). Traits: TestDefault, Test212, Test213, Test3Lts, Test3NextRc.

Adding a test:

1. Open the right *TestDefinitions (e.g. RunTestDefinitions for run).
2. Add test("description") { … } using TestInputs(os.rel / "Main.scala" -> "…").fromRoot { root => … } and os.proc(TestUtil.cli, "run", …).call(cwd = root).
3. Assert on stdout/stderr.

Helpers: TestInputs(...).fromRoot, TestUtil.cli. Test groups (CI): SCALA_CLI_IT_GROUP=1..5; see modules/integration/ for group mapping.