Fix setup_scala_toolchains, clean up test scripts

[mbland]

Description

Adds a Label() wrapper to setup_scala_toolchains() and scala_cross_version_select() to fix @rules_scala_config invisibilty build breakages under Bzlmod. Enables Bash strict mode for all test scripts via set -euo pipefail and fixes the resulting breakages.

Removes use_repo(scala_config, "rules_scala_config") from dt_patches/test_dt_patches{,_user_srcjar}/MODULE.bazel. This caused dt_patches/dt_patch_test.sh to break before adding the Label() wrapper to setup_scala_toolchains().

Also updates dt_patches/dt_patch_test.sh to use test/shell/test_runner.sh and test/shell/test_helper.sh. Replaces previous instances of its own run_test_local with the result of get_test_runner. Updates run_in_test_repo argument parsing, updates run_in_test_repo calls to use proper string quoting, and ensures any failures exit the script.

Other general test updates include:

• Adds a new dt_patches_linux job to .bazelci/presubmit.yml to run dt_patches/dt_patch_test.sh as part of the CI build.

• Sets set -euo pipefail in test_runner.sh and test_helper.sh and fixes all unbound variables and pipe failures. Updates test helpers in those files to perform better argument quoting, argument pass through, command execution, and output printing.

• Updates test helpers in test_runner.sh and test_helper.sh to show more information when the new verbose_test_output helper returns success, even when a test passes. Removes exit 0 everywhere so successful tests return control to run_test_local when verbose_test_output is in effect. Adds an exit in run_test_local when RULES_SCALA_TEST_ONLY is nonempty.

• Adds #!/usr/bin/env bash to a number of test files. This avoids having some test helper echo statements from printing the -e argument when running the test file directly. (As opposed to running them via test_all.sh or test_rules_scala.sh.)

• Adds test/shell/test_macros.sh to test_rules_scala.sh.

Updates that fixed previously incorrect behavior of specific tests include:

• Fixes test_scala_import_source_jar.sh after Bash strict mode fixes revealed underlying breakages. Specifically, if [[ $1 ]] in assert_file_exists() always returned true, which meant the function always returned true, because the src jar never existed. Also, the expected repo path was never valid under Bzlmod, since it relied on the WORKSPACE specific repo path naming convention. Changing the condition to if [[ -n "$1" ]] fulfilled the actual intention, and revealed the broken repo path and fetch_sources never being true.

  Ensures fetch_sources is True for @com_google_guava_guava_21_0 from //scala/private/extensions/dev_deps.bzl%dev_deps. Also makes the directory path to the repo Bzlmod compatible. (Fortunately, the underlying behavior the test intended to validate was already correct.)

• Fixes test_scala_classpath.sh to actually grep for the expected string. Previously is was grepping for the empty string, thanks to the unbound $method variable, and always passed. Fixing this revealed that the test would fail when run if the test target artifacts already existed. Updated it to remove the test target artifacts so that the test could run correctly every time. (Again, the underlying behavior was already correct.)

Test updates resulting from Bash strict mode that didn't fundamentally change test behavior include:

• Fixed the unbound $target_bes variable in test_build_event_protocol.sh by replacing it with ${bes_file}. The original intention appeared to be ${target}_bes.txt, and the test previously just happened to work by using a file named .txt.

• Refactored test_invalid_scalacopts.sh to use action_should_fail_with{,out}_message. This resolves the previous pipe failure after turning on Bash strict mode.

• Updates test_macros.sh to use Bash stderr redirection syntax. Overlaps with a change in Check for 'deps' attr in scala_doc rule #1740, but shouldn't conflict.

• All other test updates defined previously unbound variables and fixed improper argument quotation.

Motivation

This contains an easy fix for a basic Bzlmod breakage. In looking to provide a test for it, I went down the path of improving all the shell tests by applying Bash strict mode. This turned into a larger pull request than I intended; as always, I'm happy to split it up if so desired.

Vince Rose reported the setup_scala_toolchains breakage under Bzlmod in the #scala channel of the Bazel Slack Workspace on 2025-05-21:

• https://bazelbuild.slack.com/archives/CDCKJ2KFZ/p1747870770592779

dt_patches/dt_patch_test.sh would've caught it had I not added use_repo(scala_config, "rules_scala_config") to the MODULE.bazel files. Removing these use_repo calls reproduced the error, and they passed again once I reintroduced the proper Label instances.

Rather than add another test, I thought it was time to ensure dt_patch_test.sh behaved properly and could run in CI. Also, @jayconrod recently reminded me of Bash strict mode during the course of an internal code review. So I added Bash strict mode to dt_patch_test.sh and refactored it to ensure that a test failure properly exited the script.

That went well, so I decided to set Bash strict mode in test_runner.sh and test_helper.sh. Hilarity ensued.

Having Bash strict mode in place should greatly reduce the chances of adding tests that pass without actually doing what we think they're doing. Several of the updates show more info when
RULES_SCALA_TEST_ONLY and RULES_SCALA_TEST_VERBOSE are in effect. This helped me immensely while getting to the root of these problems, especially when defining a previously unbound variable and having a test immediately pass. These RULES_SCALA_TEST_* variables helped me verify that they were really passing, or accidentally getting by.

There's still opportunities to refactor some of the tests to use more of the existing test helpers. I could do more test script cleanup passes in one or more future pull requests.

[simuons]

Thanks, @mbland, for yet another improvement!