headroom/e2e/_lib/shims.py
JerrettDavis 3ca2ce08ae refactor(e2e): extract reusable harness into e2e/_lib
Centralize Docker / CI e2e test helpers so per-command suites can be
declarative and future commands (install, wrap, ...) can reuse the same
shim/PATH/assertion primitives without duplicating infrastructure.

The harness provides:

* Case dataclass describing one test as argv + shims + expected exit /
  stdout / stderr / files / custom callbacks
* make_shim() factory producing cross-platform executable shims (.sh on
  POSIX, .cmd on Windows) with noop / fail / record-args behaviors
* with_clean_path() context manager that isolates PATH to a minimal
  known-good value plus any extras supplied by the case
* agent_settings_path() locator mirroring headroom.cli.init so tests can
  assert the right file was written without touching private init state
* run_cases() for independent cases and run_case_sequence() for cases
  that must share scratch state (e.g. manifest-merge scenarios)

Shell / PowerShell shim-creation scripts are also shipped for CI steps
that need to drop a shim without spinning up Python first.

No behavior change in this commit - pure infrastructure. The init suite
and new subcommand suites consume the harness in follow-up commits.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-23 15:50:12 -05:00

96 lines
3.1 KiB
Python

"""Cross-platform agent binary shim factory for e2e tests.
A "shim" is a tiny executable with a given name (e.g. `claude`, `codex`) that
the harness drops into a temporary directory and prepends to PATH. It lets
tests drive `headroom init` without requiring a real Claude/Codex install.
Three behaviors are supported:
* ``noop`` — exits 0 with no output. Default.
* ``fail`` — exits 1 with a short stderr message.
* ``record-args`` — appends a JSON record of (tool, argv, cwd) to the file at
``$HEADROOM_E2E_SHIM_LOG``, then exits 0. Useful for
asserting that `init claude` invoked
`claude plugin install` with the right arguments.
"""
from __future__ import annotations
import os
import stat
import sys
from pathlib import Path
from typing import Literal
ShimBehavior = Literal["noop", "fail", "record-args"]
_NOOP_SH = """#!/usr/bin/env bash
exit 0
"""
_FAIL_SH = """#!/usr/bin/env bash
echo "${0##*/}: simulated failure" >&2
exit 1
"""
_RECORD_SH = """#!/usr/bin/env bash
tool="${0##*/}"
log="${HEADROOM_E2E_SHIM_LOG:-/dev/null}"
mkdir -p "$(dirname "$log")" 2>/dev/null || true
python3 - "$tool" "$log" "$@" <<'PY'
import json, os, sys
tool, log, *argv = sys.argv[1:]
record = {"tool": tool, "argv": argv, "cwd": os.getcwd()}
if log != "/dev/null":
with open(log, "a", encoding="utf-8") as handle:
handle.write(json.dumps(record) + "\\n")
print(f"{tool} shim executed")
PY
exit 0
"""
# Windows equivalents. Use `.cmd` so `shutil.which` and PATHEXT find them.
_NOOP_CMD = "@echo off\r\nexit /b 0\r\n"
_FAIL_CMD = "@echo off\r\necho %~n0: simulated failure 1>&2\r\nexit /b 1\r\n"
_RECORD_CMD = (
"@echo off\r\n"
"setlocal\r\n"
'if "%HEADROOM_E2E_SHIM_LOG%"=="" set HEADROOM_E2E_SHIM_LOG=NUL\r\n'
"python -c \"import json,os,sys; name=r'%~n0'; log=os.environ['HEADROOM_E2E_SHIM_LOG']; "
"rec={'tool':name,'argv':sys.argv[1:],'cwd':os.getcwd()};\r\n"
"open(log,'a',encoding='utf-8').write(json.dumps(rec)+chr(10)) if log!='NUL' else None;\r\n"
"print(f'{name} shim executed')\" %*\r\n"
"exit /b 0\r\n"
)
def _is_windows() -> bool:
return os.name == "nt" or sys.platform == "win32"
def make_shim(name: str, dir: Path, behavior: ShimBehavior = "noop") -> Path:
"""Create an executable shim named ``name`` inside ``dir``.
Returns the absolute path to the created shim. On POSIX this is a ``.sh``
file made executable and named without extension (so ``shutil.which(name)``
finds it). On Windows this is a ``.cmd`` file — again, ``shutil.which``
honours ``PATHEXT`` and will find it.
"""
dir = Path(dir)
dir.mkdir(parents=True, exist_ok=True)
if _is_windows():
body = {"noop": _NOOP_CMD, "fail": _FAIL_CMD, "record-args": _RECORD_CMD}[behavior]
path = dir / f"{name}.cmd"
path.write_text(body, encoding="utf-8")
return path
body = {"noop": _NOOP_SH, "fail": _FAIL_SH, "record-args": _RECORD_SH}[behavior]
path = dir / name
path.write_text(body, encoding="utf-8")
mode = path.stat().st_mode
path.chmod(mode | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
return path