build(release): add process-news command with PR and version marker support

RELEASING.md

@@ -131,6 +131,37 @@ The `<PR_REF>` can be:
     or `https://github.com/bazel-contrib/rules_python/pull/124/files`)
 *   Only URLs for the configured repository are accepted.
 
+### Processing News Files and PR Changes for Backports
+
+To process and merge news files into an existing release in `CHANGELOG.md`
+(e.g. after backporting a PR) and update any `VERSION_NEXT_*` markers added by
+the PR:
+
+```shell
+bazel run //tools/private/release -- \
+    process-news <VERSION> <TARGET> [<TARGET> ...]
+```
+
+The `<TARGET>` can be:
+*   A news file path (e.g., `news/3997.added.md`).
+*   A PR number (e.g., `3997` or `#3997`).
+*   A PR URL (e.g., `https://github.com/bazel-contrib/rules_python/pull/3997`).
+
+When a PR reference is passed, `process-news` resolves the files touched by the
+PR, merges its news file(s) into `CHANGELOG.md`, deletes the processed news
+file(s), and updates any `VERSION_NEXT_FEATURE` / `VERSION_NEXT_PATCH`
+placeholders in the PR's files to `<VERSION>`.
+
+Examples:
+
+```shell
+# Process a single news file
+bazel run //tools/private/release -- process-news 2.3.0 news/3997.added.md
+
+# Process all news files and update version markers for a PR
+bazel run //tools/private/release -- process-news 2.3.0 3997
+```
+
 ### Failure Behavior
 If a backport fails to process (e.g., due to cherry-pick conflicts):
 *   The failed backport checklist item will remain unchecked with

tests/tools/private/release/BUILD.bazel

@@ -31,6 +31,7 @@ py_library(
 pytest_test(
     name = "add_backports_test",
     srcs = ["add_backports_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -42,6 +43,7 @@ pytest_test(
 pytest_test(
     name = "changelog_news_test",
     srcs = ["changelog_news_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -53,6 +55,7 @@ pytest_test(
 pytest_test(
     name = "complete_prepare_test",
     srcs = ["complete_prepare_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -64,6 +67,7 @@ pytest_test(
 pytest_test(
     name = "complete_sync_changelog_test",
     srcs = ["complete_sync_changelog_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -75,6 +79,7 @@ pytest_test(
 pytest_test(
     name = "create_release_branch_test",
     srcs = ["create_release_branch_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -86,6 +91,7 @@ pytest_test(
 pytest_test(
     name = "git_test",
     srcs = ["git_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -97,6 +103,7 @@ pytest_test(
 pytest_test(
     name = "on_pr_merged_test",
     srcs = ["on_pr_merged_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -108,6 +115,7 @@ pytest_test(
 pytest_test(
     name = "promote_test",
     srcs = ["promote_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -119,6 +127,7 @@ pytest_test(
 pytest_test(
     name = "release_issue_test",
     srcs = ["release_issue_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -130,6 +139,7 @@ pytest_test(
 pytest_test(
     name = "release_test",
     srcs = ["release_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -141,6 +151,7 @@ pytest_test(
 pytest_test(
     name = "backport_create_releases_test",
     srcs = ["backport_create_releases_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -152,6 +163,7 @@ pytest_test(
 pytest_test(
     name = "prepare_test",
     srcs = ["prepare_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -163,6 +175,7 @@ pytest_test(
 pytest_test(
     name = "gh_test",
     srcs = ["gh_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -174,6 +187,7 @@ pytest_test(
 pytest_test(
     name = "backport_prepare_test",
     srcs = ["backport_prepare_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -185,6 +199,7 @@ pytest_test(
 pytest_test(
     name = "process_backports_test",
     srcs = ["process_backports_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -196,6 +211,19 @@ pytest_test(
 pytest_test(
     name = "create_rc_test",
     srcs = ["create_rc_test.py"],
+    python_version = "3.14",
+    target_compatible_with = NOT_WINDOWS,
+    deps = [
+        ":conftest",
+        ":release_test_helper",
+        "//tools/private/release:release_lib",
+    ],
+)
+
+pytest_test(
+    name = "process_news_test",
+    srcs = ["process_news_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",
@@ -207,6 +235,7 @@ pytest_test(
 pytest_test(
     name = "utils_test",
     srcs = ["utils_test.py"],
+    python_version = "3.14",
     target_compatible_with = NOT_WINDOWS,
     deps = [
         ":conftest",

tests/tools/private/release/gh_test.py

@@ -1,7 +1,14 @@
+import subprocess
+
 import pytest
 
 from tools.private.release import shell
-from tools.private.release.gh import CreatePrError, GitHub
+from tools.private.release.gh import (
+    CreatePrError,
+    GetPrError,
+    GitHub,
+    InvalidPrRefError,
+)
 from tools.private.release.git import Git
 
 pytest_plugins = ["tests.tools.private.release.release_test_helper"]
@@ -51,14 +58,16 @@ def test_resolve_pr_number_url_other_repo(mocker, gh):
     mock_run_cmd = mocker.patch("tools.private.release.gh.run_cmd")
     # URL for a different repo should fail immediately without calling gh
     url = "https://github.com/other-owner/other-repo/pull/126"
-    with pytest.raises(ValueError, match="URL is not for the configured repository"):
+    with pytest.raises(
+        InvalidPrRefError, match="URL is not for the configured repository"
+    ):
         gh.resolve_pr_number(url)
     mock_run_cmd.assert_not_called()
 
 
 def test_resolve_pr_number_invalid(mocker, gh):
     mock_run_cmd = mocker.patch("tools.private.release.gh.run_cmd")
-    with pytest.raises(ValueError, match="Could not resolve PR reference"):
+    with pytest.raises(InvalidPrRefError, match="Could not resolve PR reference"):
         gh.resolve_pr_number("invalid-ref")
     mock_run_cmd.assert_not_called()
 
@@ -96,6 +105,29 @@ def mock_run(*args, **kwargs):
     assert captured_body["content"] == "new body content"
 
 
+def test_get_pr_files(gh, auto_patch_cmd_helpers):
+    auto_patch_cmd_helpers.run_gh.return_value = (
+        '{"files": [{"path": "news/123.added.md"}, {"path": "python/foo.py"}]}'
+    )
+    files = gh.get_pr_files(123)
+    assert files == ["news/123.added.md", "python/foo.py"]
+    auto_patch_cmd_helpers.run_gh.assert_called_with(
+        "pr",
+        "view",
+        "123",
+        "--json=files",
+        "--repo=my-owner/my-repo",
+        check=True,
+        capture_output=True,
+    )
+
+
+def test_get_pr_files_not_found(gh, auto_patch_cmd_helpers):
+    auto_patch_cmd_helpers.run_gh.side_effect = subprocess.CalledProcessError(1, ["gh"])
+    with pytest.raises(GetPrError, match="Failed to get PR #123 on my-owner/my-repo"):
+        gh.get_pr_files(123)
+
+
 def test_create_pr_success(gh, auto_patch_cmd_helpers):
     auto_patch_cmd_helpers.run_gh.return_value = (
         "https://github.com/my-owner/my-repo/pull/123"
@@ -121,8 +153,6 @@ def test_create_pr_success(gh, auto_patch_cmd_helpers):
 
 
 def test_create_pr_failure_raises_create_pr_error(gh, auto_patch_cmd_helpers):
-    import subprocess
-
     err = subprocess.CalledProcessError(
         1,
         ["gh", "pr", "create"],