"""Tests for the post-pull syntax guard in ``hermes update``. When a bad commit lands on ``main`` with a syntax error in a critical file (e.g. orphan merge-conflict markers in ``hermes_cli/config.py``), the CLI becomes unbootable — every ``hermes`` invocation imports those files at startup. The guard validates them after ``git pull`` and rolls back to the pre-pull SHA on failure so the user's install stays runnable. Reference incident: PR #28452 (May 18, 2026) shipped unresolved conflict markers in ``hermes_cli/config.py``; users who ran ``hermes update`` in the 7-minute window before #28458 landed could not run any ``hermes`` command afterward. """ from __future__ import annotations from pathlib import Path from types import SimpleNamespace from hermes_cli import main as hermes_main # --------------------------------------------------------------------------- # _capture_head_sha # --------------------------------------------------------------------------- def test_capture_head_sha_returns_stripped_sha(monkeypatch, tmp_path): def fake_run(cmd, **kwargs): assert cmd[-2:] == ["rev-parse", "HEAD"] return SimpleNamespace(stdout="deadbeefcafe\n", returncode=0) monkeypatch.setattr(hermes_main.subprocess, "run", fake_run) assert hermes_main._capture_head_sha(["git"], tmp_path) == "deadbeefcafe" def test_capture_head_sha_returns_none_on_git_failure(monkeypatch, tmp_path): import subprocess as _sp def fake_run(cmd, **kwargs): raise _sp.CalledProcessError(returncode=128, cmd=cmd) monkeypatch.setattr(hermes_main.subprocess, "run", fake_run) assert hermes_main._capture_head_sha(["git"], tmp_path) is None def test_capture_head_sha_returns_none_on_empty_output(monkeypatch, tmp_path): def fake_run(cmd, **kwargs): return SimpleNamespace(stdout="\n", returncode=0) monkeypatch.setattr(hermes_main.subprocess, "run", fake_run) assert hermes_main._capture_head_sha(["git"], tmp_path) is None # --------------------------------------------------------------------------- # _validate_critical_files_syntax # --------------------------------------------------------------------------- def _populate_critical_tree(root: Path, *, broken_file: str | None = None) -> None: """Create stub files for every entry in ``_UPDATE_CRITICAL_FILES``. If ``broken_file`` is given, that file gets orphan merge-conflict markers (the exact failure mode from PR #28452). """ broken_payload = ( "x = {\n" ' "a": 1,\n' "<<<<<<< HEAD\n" ' "b": 2,\n' "=======\n" ' "c": 0b6d673e7,\n' # invalid binary literal — the actual error users saw ">>>>>>> 0b6d673e7\n" "}\n" ) for relpath in hermes_main._UPDATE_CRITICAL_FILES: path = root / relpath path.parent.mkdir(parents=True, exist_ok=True) if relpath == broken_file: path.write_text(broken_payload) else: path.write_text("# stub\n") def test_validate_critical_files_syntax_ok_when_all_files_parse(tmp_path): _populate_critical_tree(tmp_path) ok, failing_path, error = hermes_main._validate_critical_files_syntax(tmp_path) assert ok is True assert failing_path is None assert error is None def test_validate_critical_files_syntax_detects_conflict_markers(tmp_path): """The exact PR #28452 failure mode: orphan ``<<<<<<<`` in config.py.""" _populate_critical_tree(tmp_path, broken_file="hermes_cli/config.py") ok, failing_path, error = hermes_main._validate_critical_files_syntax(tmp_path) assert ok is False assert failing_path is not None and failing_path.endswith("hermes_cli/config.py") assert error is not None # The error mentions either the syntax error itself or the file path — # either is enough proof we caught the bad commit. assert "SyntaxError" in str(error) or "config.py" in str(error) def test_validate_critical_files_syntax_detects_break_in_main_py(tmp_path): _populate_critical_tree(tmp_path, broken_file="hermes_cli/main.py") ok, failing_path, _ = hermes_main._validate_critical_files_syntax(tmp_path) assert ok is False assert failing_path is not None and failing_path.endswith("hermes_cli/main.py") def test_validate_critical_files_syntax_tolerates_missing_files(tmp_path): """A refactor may legitimately remove one of the critical files — the guard should skip missing files, not falsely flag the install as broken.""" # Populate everything except hermes_constants.py for relpath in hermes_main._UPDATE_CRITICAL_FILES: if relpath == "hermes_constants.py": continue path = tmp_path / relpath path.parent.mkdir(parents=True, exist_ok=True) path.write_text("# stub\n") ok, failing_path, error = hermes_main._validate_critical_files_syntax(tmp_path) assert ok is True assert failing_path is None assert error is None # --------------------------------------------------------------------------- # Repo invariant — the production tree itself must always pass the guard. # This catches the case where ``main`` ships a syntax error before the next # release; if a future ``hermes update`` would brick users, this test fails # in CI first. # --------------------------------------------------------------------------- def test_production_tree_passes_syntax_guard(): """The repo itself must always satisfy the guard the update command runs.""" repo_root = Path(__file__).resolve().parents[2] ok, failing_path, error = hermes_main._validate_critical_files_syntax(repo_root) assert ok is True, ( f"Critical-path file {failing_path} fails to parse on current main; " f"hermes update would brick users. Error: {error}" )