fix: BCR presubmit (#38)

- Add a child workspace to use as the BCR presubmit test.
- Update BCR presubmit config to run tests in the new workspace.

Related to
bazelbuild/bazel-central-registry#1390.

.bazelignore

@@ -0,0 +1 @@
+test/bcr_test

.bcr/presubmit.yml

@@ -1,3 +1,4 @@
+module_path: test/bcr_test
 matrix:
   platform:
     - centos7
@@ -6,8 +7,8 @@ matrix:
     - macos
     - windows
 tasks:
-  verify_targets:
-    name: Verify build targets
+  run_test_module:
+    name: Run test module
     platform: ${{ platform }}
-    build_targets:
-      - "@bazel_features//test:tests"
+    test_targets:
+      - "//..."

.github/workflows/ci.yaml

@@ -16,7 +16,26 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  test:
+  unit_tests:
     uses: bazel-contrib/.github/.github/workflows/bazel.yaml@v5
     with:
       folders: '["."]'
+  bcr_test:
+    uses: bazel-contrib/.github/.github/workflows/bazel.yaml@v5
+    with:
+      folders: '["test/bcr_test"]'
+      exclude: |
+        [
+          {"bzlmodEnabled": false},
+          {"bazelversion": "5.4.0"}
+        ]
+  test:
+    runs-on: ubuntu-latest
+    needs:
+      - unit_tests
+      - bcr_test
+    if: ${{ always() }}
+    steps:
+      - uses: cgrindel/gha_join_jobs@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}

test/bcr_test/.bazelrc

@@ -0,0 +1 @@
+try-import %workspace%/.bazelrc.user

test/bcr_test/.bazelversion

@@ -0,0 +1 @@
+7.0.2

test/bcr_test/BUILD.bazel

@@ -0,0 +1,3 @@
+load(":test.bzl", "bazel_features_test_suite")
+
+bazel_features_test_suite(name = "bazel_features_test")

test/bcr_test/MODULE.bazel

@@ -0,0 +1,6 @@
+bazel_dep(name = "bazel_skylib", version = "1.4.2")
+bazel_dep(name = "bazel_features")
+local_path_override(
+    module_name = "bazel_features",
+    path = "../..",
+)

test/bcr_test/test.bzl

@@ -0,0 +1,19 @@
+load("@bazel_features//:features.bzl", "bazel_features")
+load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
+
+"""Tests for `bazel_features` module."""
+
+def _is_bzlmod_enabled_test(ctx):
+    env = unittest.begin(ctx)
+
+    asserts.true(env, bazel_features.external_deps.is_bzlmod_enabled)
+
+    return unittest.end(env)
+
+is_bzlmod_enabled_test = unittest.make(_is_bzlmod_enabled_test)
+
+def bazel_features_test_suite(name):
+    return unittest.suite(
+        name,
+        is_bzlmod_enabled_test,
+    )