feat: test bzlmod usage on CI (#16319)

Closes #16319

COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/16319 from protocolbuffers:bcr d66845cfcb
PiperOrigin-RevId: 619939078

.github/workflows/test_bazel.yml

@@ -0,0 +1,23 @@
+name: Bazel
+
+# Controls when the action will run.
+on:
+  # Triggers the workflow on push or pull request events but only for the main branch
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+concurrency:
+    # Cancel previous actions from the same PR or branch except 'main' branch.
+    # See https://docs.github.com/en/actions/using-jobs/using-concurrency and https://docs.github.com/en/actions/learn-github-actions/contexts for more info.
+    group: concurrency-group::${{ github.workflow }}::${{ github.event.pull_request.number > 0 && format('pr-{0}', github.event.pull_request.number) || github.ref_name }}${{ github.ref_name == 'main' && format('::{0}', github.run_id) || ''}}
+    cancel-in-progress: ${{ github.ref_name != 'main' }}
+
+jobs:
+  test:
+    uses: bazel-contrib/.github/.github/workflows/bazel.yaml@v6
+    with:
+      folders: '["examples"]'

.gitignore

@@ -213,3 +213,6 @@ compile_commands.json
 
 # Ignore GHA NodeJS files
 .github/**/node_modules/
+
+# Ignore Bzlmod lock file until it is more stable
+MODULE.bazel.lock

MODULE.bazel

@@ -1,2 +1,23 @@
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/protocolbuffers/protobuf/issues/14313
+module(
+    name = "protobuf",
+    compatibility_level = 1,
+    version = "27.0",
+)
+
+# LOWER BOUND dependency versions.
+# Bzlmod follows MVS:
+# https://bazel.build/versions/6.0.0/build/bzlmod#version-resolution
+# Thus the highest version in their module graph is resolved.
+bazel_dep(name = "abseil-cpp", repo_name = "com_google_absl", version = "20230802.0.bcr.1")
+bazel_dep(name = "bazel_skylib", version = "1.4.1")
+bazel_dep(name = "jsoncpp", version = "1.9.5")
+bazel_dep(name = "rules_cc", version = "0.0.9")
+bazel_dep(name = "rules_java", version = "4.0.0")
+bazel_dep(name = "rules_jvm_external", version = "5.1")
+bazel_dep(name = "rules_pkg", version = "0.7.0")
+bazel_dep(name = "rules_proto", version = "4.0.0")
+bazel_dep(name = "rules_python", version = "0.10.2")
+bazel_dep(name = "platforms", version = "0.0.8")
+bazel_dep(name = "zlib", version = "1.2.11")

examples/.bazelversion

@@ -0,0 +1 @@
+7.1.0

examples/BUILD.bazel

@@ -4,6 +4,7 @@
 # the WORKSPACE file in the same directory with this BUILD file for an
 # example.
 
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_proto_library")
 load("@rules_java//java:defs.bzl", "java_binary", "java_lite_proto_library", "java_proto_library")
 load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
@@ -113,6 +114,14 @@ java_binary(
     deps = [":addressbook_java_lite_proto"],
 )
 
+build_test(
+    name = "test",
+    targets = [
+        ":add_person_cpp",
+        ":add_person_java",
+    ],
+)
+
 # Files included in all source distributions
 pkg_files(
     name = "dist_files",

examples/MODULE.bazel

@@ -0,0 +1,13 @@
+"""Bazel module dependencies"""
+bazel_dep(name = "protobuf", version = "0.0.0", dev_dependency = True, repo_name = "com_google_protobuf")
+
+local_path_override(
+    module_name = "protobuf",
+    path = "..",
+)
+
+bazel_dep(name = "bazel_skylib", version = "1.0.3")
+bazel_dep(name = "rules_cc", version = "0.0.1")
+bazel_dep(name = "rules_java", version = "7.3.0")
+bazel_dep(name = "rules_pkg", version = "0.7.0")
+bazel_dep(name = "rules_proto", version = "4.0.0")

examples/WORKSPACE

@@ -28,6 +28,15 @@ local_repository(
     path = "..",
 )
 
+# Needed because protobuf_deps brings rules_python 0.26.0 which is broken:
+# https://github.com/bazelbuild/rules_python/issues/1543
+http_archive(
+    name = "rules_python",
+    sha256 = "5868e73107a8e85d8f323806e60cad7283f34b32163ea6ff1020cf27abef6036",
+    strip_prefix = "rules_python-0.25.0",
+    url = "https://github.com/bazelbuild/rules_python/releases/download/0.25.0/rules_python-0.25.0.tar.gz",
+)
+
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
 
 protobuf_deps()

examples/WORKSPACE.bzlmod

@@ -0,0 +1 @@
+# This file shadows WORKSPACE in builds with `--enable_bzlmod`

src/google/protobuf/util/BUILD.bazel

@@ -162,8 +162,8 @@ cc_library(
     hdrs = ["time_util.h"],
     strip_include_prefix = "/src",
     visibility = [
-        "//:__subpackages__",
-        "@com_google_protobuf_examples//:__subpackages__",
+        # Needed when building from within the /examples repository
+        "//visibility:public",
     ],
     deps = [
         "//src/google/protobuf",