test(tools): auto-patch release CLI helpers in conftest.py

tests/tools/private/release/BUILD.bazel

@@ -4,7 +4,10 @@ load("//tests/support/pytest_test:pytest_test.bzl", "pytest_test")
 
 py_library(
     name = "release_test_helper",
-    srcs = ["release_test_helper.py"],
+    srcs = [
+        "conftest.py",
+        "release_test_helper.py",
+    ],
     target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         "//tools/private/release:mock_gh",

tests/tools/private/release/conftest.py

@@ -0,0 +1,50 @@
+import dataclasses
+from unittest.mock import MagicMock
+
+import pytest
+
+pytest_plugins = ["tests.tools.private.release.release_test_helper"]
+
+
+@dataclasses.dataclass
+class AutoPatchCmdHelpers:
+    """Dataclass holding mocked command helpers."""
+
+    run_cmd: MagicMock
+    run_git: MagicMock
+    run_gh: MagicMock
+
+
+@pytest.fixture(name="mock_run_cmd")
+def fixture_mock_run_cmd(mocker):
+    """Fixture to patch shell.run_cmd and its imports in git and gh modules."""
+    mock = mocker.patch("tools.private.release.shell.run_cmd")
+    mocker.patch("tools.private.release.git.run_cmd", mock)
+    mocker.patch("tools.private.release.gh.run_cmd", mock)
+    return mock
+
+
+@pytest.fixture(name="mock_run_git")
+def fixture_mock_run_git(mocker):
+    """Fixture to patch Git._run_git."""
+    return mocker.patch("tools.private.release.git.Git._run_git")
+
+
+@pytest.fixture(name="mock_run_gh")
+def fixture_mock_run_gh(mocker):
+    """Fixture to patch GitHub._run_gh."""
+    return mocker.patch("tools.private.release.gh.GitHub._run_gh")
+
+
+@pytest.fixture(name="auto_patch_cmd_helpers", autouse=True)
+def fixture_auto_patch_cmd_helpers(mock_run_cmd, mock_run_git, mock_run_gh):
+    """Automatically patches run_cmd, Git, and GitHub CLI helpers.
+
+    This prevents tests from executing command line tools that could have
+    side-effects.
+    """
+    return AutoPatchCmdHelpers(
+        run_cmd=mock_run_cmd,
+        run_git=mock_run_git,
+        run_gh=mock_run_gh,
+    )

tests/tools/private/release/gh_test.py

@@ -1,6 +1,8 @@
 import pytest
 
+from tools.private.release import shell
 from tools.private.release.gh import GitHub
+from tools.private.release.git import Git
 
 pytest_plugins = ["tests.tools.private.release.release_test_helper"]
 
@@ -59,3 +61,19 @@ def test_resolve_pr_number_invalid(mocker, gh):
     with pytest.raises(ValueError, match="Could not resolve PR reference"):
         gh.resolve_pr_number("invalid-ref")
     mock_run_cmd.assert_not_called()
+
+
+def test_auto_patched_helpers_prevent_real_execution(auto_patch_cmd_helpers):
+    # Calling run_cmd directly hits the mock
+    shell.run_cmd("echo", "test")
+    auto_patch_cmd_helpers.run_cmd.assert_called_with("echo", "test")
+
+    # Git._run_git hits the mock
+    git = Git(".")
+    git._run_git("status")
+    auto_patch_cmd_helpers.run_git.assert_called_with("status")
+
+    # GitHub._run_gh hits the mock
+    gh_obj = GitHub("foo/bar")
+    gh_obj._run_gh("issue", "list")
+    auto_patch_cmd_helpers.run_gh.assert_called_with("issue", "list")