feat(scripts): add Python check-prerequisites PoC (#3302)

* feat(scripts): add Python check-prerequisites PoC

* fix(scripts): address check-prerequisites parity feedback

* test(scripts): label PowerShell prerequisite parity cases

---------

Co-authored-by: root <kinsonnee@gmail.com>
This commit is contained in:
WOLIKIMCHENG
2026-07-07 06:54:31 +08:00
committed by GitHub
parent b8d27e472f
commit 73f77c200f
3 changed files with 756 additions and 0 deletions

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#!/usr/bin/env python3
"""Consolidated prerequisite checking script."""
from __future__ import annotations
import json
import sys
from dataclasses import dataclass
from pathlib import Path
try:
from common import FeaturePaths, format_speckit_command, get_feature_paths
except ImportError: # pragma: no cover - direct execution from unusual cwd
sys.path.insert(0, str(Path(__file__).resolve().parent))
from common import FeaturePaths, format_speckit_command, get_feature_paths
def _json_line(payload: object) -> str:
return json.dumps(payload, ensure_ascii=False, separators=(",", ":")) + "\n"
HELP_TEXT = """Usage: check_prerequisites.py [OPTIONS]
Consolidated prerequisite checking for Spec-Driven Development workflow.
OPTIONS:
--json Output in JSON format
--require-tasks Require tasks.md to exist (for implementation phase)
--include-tasks Include tasks.md in AVAILABLE_DOCS list
--paths-only Only output path variables (no prerequisite validation)
--help, -h Show this help message
EXAMPLES:
# Check task prerequisites (plan.md required)
./check_prerequisites.py --json
# Check implementation prerequisites (plan.md + tasks.md required)
./check_prerequisites.py --json --require-tasks --include-tasks
# Get feature paths only (no validation)
./check_prerequisites.py --paths-only
"""
@dataclass(frozen=True)
class Args:
json_mode: bool = False
require_tasks: bool = False
include_tasks: bool = False
paths_only: bool = False
def _parse_args(argv: list[str]) -> Args:
json_mode = False
require_tasks = False
include_tasks = False
paths_only = False
for arg in argv:
if arg == "--json":
json_mode = True
elif arg == "--require-tasks":
require_tasks = True
elif arg == "--include-tasks":
include_tasks = True
elif arg == "--paths-only":
paths_only = True
elif arg in {"--help", "-h"}:
sys.stdout.write(HELP_TEXT)
raise SystemExit(0)
else:
print(
f"ERROR: Unknown option '{arg}'. Use --help for usage information.",
file=sys.stderr,
)
raise SystemExit(1)
return Args(
json_mode=json_mode,
require_tasks=require_tasks,
include_tasks=include_tasks,
paths_only=paths_only,
)
def _dir_has_entries(path: Path) -> bool:
try:
return path.is_dir() and any(path.iterdir())
except OSError:
return False
def _available_docs(paths: FeaturePaths, include_tasks: bool) -> list[str]:
docs: list[str] = []
if paths.research.is_file():
docs.append("research.md")
if paths.data_model.is_file():
docs.append("data-model.md")
if _dir_has_entries(paths.contracts_dir):
docs.append("contracts/")
if paths.quickstart.is_file():
docs.append("quickstart.md")
if include_tasks and paths.tasks.is_file():
docs.append("tasks.md")
return docs
def _print_paths_only(paths: FeaturePaths, json_mode: bool) -> None:
if json_mode:
sys.stdout.write(
_json_line(
{
"REPO_ROOT": str(paths.repo_root),
"BRANCH": paths.current_branch,
"FEATURE_DIR": str(paths.feature_dir),
"FEATURE_SPEC": str(paths.feature_spec),
"IMPL_PLAN": str(paths.impl_plan),
"TASKS": str(paths.tasks),
}
)
)
return
print(f"REPO_ROOT: {paths.repo_root}")
print(f"BRANCH: {paths.current_branch}")
print(f"FEATURE_DIR: {paths.feature_dir}")
print(f"FEATURE_SPEC: {paths.feature_spec}")
print(f"IMPL_PLAN: {paths.impl_plan}")
print(f"TASKS: {paths.tasks}")
def _check_file(path: Path, description: str) -> None:
marker = "" if path.is_file() else ""
print(f" {marker} {description}")
def _check_dir(path: Path, description: str) -> None:
marker = "" if _dir_has_entries(path) else ""
print(f" {marker} {description}")
def _print_text_results(paths: FeaturePaths, include_tasks: bool) -> None:
print(f"FEATURE_DIR:{paths.feature_dir}")
print("AVAILABLE_DOCS:")
_check_file(paths.research, "research.md")
_check_file(paths.data_model, "data-model.md")
_check_dir(paths.contracts_dir, "contracts/")
_check_file(paths.quickstart, "quickstart.md")
if include_tasks:
_check_file(paths.tasks, "tasks.md")
def main(argv: list[str] | None = None) -> int:
args = _parse_args(list(argv if argv is not None else sys.argv[1:]))
try:
paths = get_feature_paths(
no_persist=args.paths_only,
script_file=Path(__file__),
)
except SystemExit as exc:
if exc.code == 0:
return 0
print("ERROR: Failed to resolve feature paths", file=sys.stderr)
return int(exc.code) if isinstance(exc.code, int) else 1
if args.paths_only:
_print_paths_only(paths, args.json_mode)
return 0
if not paths.feature_dir.is_dir():
print(f"ERROR: Feature directory not found: {paths.feature_dir}", file=sys.stderr)
print(
f"Run {format_speckit_command('specify', paths.repo_root)} first to create the feature structure.",
file=sys.stderr,
)
return 1
if not paths.impl_plan.is_file():
print(f"ERROR: plan.md not found in {paths.feature_dir}", file=sys.stderr)
print(
f"Run {format_speckit_command('plan', paths.repo_root)} first to create the implementation plan.",
file=sys.stderr,
)
return 1
if args.require_tasks and not paths.tasks.is_file():
print(f"ERROR: tasks.md not found in {paths.feature_dir}", file=sys.stderr)
print(
f"Run {format_speckit_command('tasks', paths.repo_root)} first to create the task list.",
file=sys.stderr,
)
return 1
docs = _available_docs(paths, args.include_tasks)
if args.json_mode:
sys.stdout.write(
_json_line({"FEATURE_DIR": str(paths.feature_dir), "AVAILABLE_DOCS": docs})
)
else:
_print_text_results(paths, args.include_tasks)
return 0
if __name__ == "__main__":
raise SystemExit(main())

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scripts/python/common.py Normal file
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"""Shared helpers for Spec Kit Python scripts."""
from __future__ import annotations
import json
import os
import sys
from dataclasses import dataclass
from pathlib import Path
def _trim_trailing_separators(value: Path) -> str:
text = str(value)
while len(text) > 1 and text.endswith((os.sep, "/")):
text = text[:-1]
return text
def find_specify_root(start_dir: Path | None = None) -> Path | None:
current = (start_dir or Path.cwd()).resolve()
while True:
if (current / ".specify").is_dir():
return current
parent = current.parent
if parent == current:
return None
current = parent
def resolve_specify_init_dir() -> Path:
raw = os.environ.get("SPECIFY_INIT_DIR", "")
candidate = Path(raw)
if not candidate.is_absolute():
candidate = Path.cwd() / candidate
try:
init_root = candidate.resolve(strict=True)
except OSError:
print(
f"ERROR: SPECIFY_INIT_DIR does not point to an existing directory: {raw}",
file=sys.stderr,
)
raise SystemExit(1)
if not init_root.is_dir():
print(
f"ERROR: SPECIFY_INIT_DIR does not point to an existing directory: {raw}",
file=sys.stderr,
)
raise SystemExit(1)
if not (init_root / ".specify").is_dir():
print(
"ERROR: SPECIFY_INIT_DIR is not a Spec Kit project "
f"(no .specify/ directory): {init_root}",
file=sys.stderr,
)
raise SystemExit(1)
return init_root
def get_repo_root(script_file: Path | None = None) -> Path:
if os.environ.get("SPECIFY_INIT_DIR"):
return resolve_specify_init_dir()
specify_root = find_specify_root()
if specify_root is not None:
return specify_root
if script_file is not None:
script_root = find_specify_root(script_file.resolve().parent)
if script_root is not None:
return script_root
# Installed scripts live at .specify/scripts/python/<script>.py.
return script_file.resolve().parents[3]
return Path.cwd().resolve()
def get_current_branch() -> str:
return os.environ.get("SPECIFY_FEATURE", "")
def read_feature_json_feature_directory(repo_root: Path) -> str:
feature_json = repo_root / ".specify" / "feature.json"
if not feature_json.is_file():
return ""
try:
data = json.loads(feature_json.read_text(encoding="utf-8"))
except (OSError, json.JSONDecodeError):
return ""
value = data.get("feature_directory") if isinstance(data, dict) else None
return value if isinstance(value, str) else ""
def _json_dump(data: dict[str, str]) -> str:
return json.dumps(data, ensure_ascii=False, separators=(",", ":")) + "\n"
def persist_feature_json(repo_root: Path, feature_dir_value: str) -> None:
value = feature_dir_value
try:
relative = Path(value)
if relative.is_absolute():
try:
value = relative.resolve().relative_to(repo_root.resolve()).as_posix()
except ValueError:
value = str(relative)
except OSError:
pass
current = read_feature_json_feature_directory(repo_root)
if current == value:
return
specify_dir = repo_root / ".specify"
specify_dir.mkdir(parents=True, exist_ok=True)
(specify_dir / "feature.json").write_text(
_json_dump({"feature_directory": value}),
encoding="utf-8",
)
@dataclass(frozen=True)
class FeaturePaths:
repo_root: Path
current_branch: str
feature_dir: Path
feature_spec: Path
impl_plan: Path
tasks: Path
research: Path
data_model: Path
quickstart: Path
contracts_dir: Path
def get_feature_paths(
*, no_persist: bool = False, script_file: Path | None = None
) -> FeaturePaths:
repo_root = get_repo_root(script_file)
current_branch = get_current_branch()
feature_dir_raw = os.environ.get("SPECIFY_FEATURE_DIRECTORY", "")
if feature_dir_raw:
feature_dir = Path(feature_dir_raw)
if not feature_dir.is_absolute():
feature_dir = repo_root / feature_dir
if not no_persist:
persist_feature_json(repo_root, feature_dir_raw)
elif (repo_root / ".specify" / "feature.json").is_file():
stored = read_feature_json_feature_directory(repo_root)
if not stored:
print(
"ERROR: Feature directory not found. Set SPECIFY_FEATURE_DIRECTORY "
"or ensure .specify/feature.json contains feature_directory.",
file=sys.stderr,
)
raise SystemExit(1)
feature_dir = Path(stored)
if not feature_dir.is_absolute():
feature_dir = repo_root / feature_dir
else:
print(
"ERROR: Feature directory not found. Set SPECIFY_FEATURE_DIRECTORY "
"or run the specify command to create .specify/feature.json.",
file=sys.stderr,
)
raise SystemExit(1)
if not current_branch:
current_branch = Path(_trim_trailing_separators(feature_dir)).name
return FeaturePaths(
repo_root=repo_root,
current_branch=current_branch,
feature_dir=feature_dir,
feature_spec=feature_dir / "spec.md",
impl_plan=feature_dir / "plan.md",
tasks=feature_dir / "tasks.md",
research=feature_dir / "research.md",
data_model=feature_dir / "data-model.md",
quickstart=feature_dir / "quickstart.md",
contracts_dir=feature_dir / "contracts",
)
def get_invoke_separator(repo_root: Path) -> str:
integration_json = repo_root / ".specify" / "integration.json"
if not integration_json.is_file():
return "."
try:
state = json.loads(integration_json.read_text(encoding="utf-8"))
key = state.get("default_integration") or state.get("integration") or ""
settings = state.get("integration_settings")
if isinstance(key, str) and isinstance(settings, dict):
entry = settings.get(key)
if isinstance(entry, dict) and entry.get("invoke_separator") in {".", "-"}:
return entry["invoke_separator"]
except (OSError, json.JSONDecodeError):
pass
return "."
def format_speckit_command(command_name: str, repo_root: Path) -> str:
separator = get_invoke_separator(repo_root)
name = command_name.lstrip("/")
if name.startswith("speckit."):
name = name[len("speckit.") :]
elif name.startswith("speckit-"):
name = name[len("speckit-") :]
name = name.replace(".", separator)
return f"/speckit{separator}{name}"

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"""Parity tests for the Python check-prerequisites PoC."""
from __future__ import annotations
import json
import os
import shutil
import subprocess
import sys
from pathlib import Path
import pytest
from tests.conftest import requires_bash
PROJECT_ROOT = Path(__file__).resolve().parent.parent
COMMON_SH = PROJECT_ROOT / "scripts" / "bash" / "common.sh"
CHECK_PREREQS_SH = PROJECT_ROOT / "scripts" / "bash" / "check-prerequisites.sh"
COMMON_PS = PROJECT_ROOT / "scripts" / "powershell" / "common.ps1"
CHECK_PREREQS_PS = PROJECT_ROOT / "scripts" / "powershell" / "check-prerequisites.ps1"
COMMON_PY = PROJECT_ROOT / "scripts" / "python" / "common.py"
CHECK_PREREQS_PY = PROJECT_ROOT / "scripts" / "python" / "check_prerequisites.py"
HAS_PWSH = shutil.which("pwsh") is not None
_WINDOWS_POWERSHELL = (
shutil.which("powershell.exe") or shutil.which("powershell")
) if os.name == "nt" else None
def _install_scripts(repo: Path) -> None:
bash_dir = repo / ".specify" / "scripts" / "bash"
bash_dir.mkdir(parents=True, exist_ok=True)
shutil.copy(COMMON_SH, bash_dir / "common.sh")
shutil.copy(CHECK_PREREQS_SH, bash_dir / "check-prerequisites.sh")
ps_dir = repo / ".specify" / "scripts" / "powershell"
ps_dir.mkdir(parents=True, exist_ok=True)
shutil.copy(COMMON_PS, ps_dir / "common.ps1")
shutil.copy(CHECK_PREREQS_PS, ps_dir / "check-prerequisites.ps1")
py_dir = repo / ".specify" / "scripts" / "python"
py_dir.mkdir(parents=True, exist_ok=True)
shutil.copy(COMMON_PY, py_dir / "common.py")
shutil.copy(CHECK_PREREQS_PY, py_dir / "check_prerequisites.py")
def _write_feature_json(
repo: Path, feature_directory: str = "specs/001-my-feature"
) -> None:
(repo / ".specify" / "feature.json").write_text(
json.dumps({"feature_directory": feature_directory}, separators=(",", ":"))
+ "\n",
encoding="utf-8",
)
def _clean_env() -> dict[str, str]:
env = os.environ.copy()
for key in list(env):
if key.startswith("SPECIFY_"):
env.pop(key)
return env
def _git_init(repo: Path) -> None:
subprocess.run(["git", "init", "-q"], cwd=repo, check=True)
subprocess.run(
["git", "config", "user.email", "test@example.com"], cwd=repo, check=True
)
subprocess.run(["git", "config", "user.name", "Test User"], cwd=repo, check=True)
subprocess.run(
["git", "commit", "--allow-empty", "-m", "init", "-q"], cwd=repo, check=True
)
@pytest.fixture
def prereq_repo(tmp_path: Path) -> Path:
repo = tmp_path / "proj"
repo.mkdir()
_git_init(repo)
(repo / ".specify").mkdir()
_install_scripts(repo)
return repo
def _py_cmd(repo: Path, *args: str) -> list[str]:
script = repo / ".specify" / "scripts" / "python" / "check_prerequisites.py"
return [sys.executable, str(script), *args]
def _repo_copy_py_cmd(repo: Path, *args: str) -> list[str]:
script = repo / "scripts" / "python" / "check_prerequisites.py"
return [sys.executable, str(script), *args]
def _bash_cmd(repo: Path, *args: str) -> list[str]:
script = repo / ".specify" / "scripts" / "bash" / "check-prerequisites.sh"
return ["bash", str(script), *args]
def _ps_cmd(repo: Path, *args: str) -> list[str]:
script = repo / ".specify" / "scripts" / "powershell" / "check-prerequisites.ps1"
exe = "pwsh" if HAS_PWSH else _WINDOWS_POWERSHELL
return [exe, "-NoProfile", "-File", str(script), *args]
def _run(
cmd: list[str], repo: Path, env: dict[str, str] | None = None
) -> subprocess.CompletedProcess[str]:
return subprocess.run(
cmd,
cwd=repo,
capture_output=True,
text=True,
check=False,
env=env or _clean_env(),
)
def _json_stdout(result: subprocess.CompletedProcess[str]) -> object:
return json.loads(result.stdout)
def _normalize_status_text(text: str) -> str:
return (
text.replace("", " [OK] ")
.replace("", " [FAIL] ")
.replace("\r\n", "\n")
)
def _normalize_help_text(text: str) -> str:
normalized = text.replace("\r\n", "\n").replace(
"check-prerequisites.sh", "check_prerequisites.py"
)
return "\n".join("" if not line.strip() else line for line in normalized.split("\n"))
@requires_bash
@pytest.mark.parametrize(
"args",
[
("--json",),
("--json", "--include-tasks"),
("--json", "--require-tasks", "--include-tasks"),
("--json", "--paths-only"),
],
)
def test_python_json_output_matches_bash(prereq_repo: Path, args: tuple[str, ...]) -> None:
feat = prereq_repo / "specs" / "001-my-feature"
feat.mkdir(parents=True)
(feat / "plan.md").write_text("# plan\n", encoding="utf-8")
(feat / "tasks.md").write_text("# tasks\n", encoding="utf-8")
(feat / "research.md").write_text("# research\n", encoding="utf-8")
(feat / "data-model.md").write_text("# model\n", encoding="utf-8")
(feat / "quickstart.md").write_text("# quickstart\n", encoding="utf-8")
(feat / "contracts" / "v1").mkdir(parents=True)
_write_feature_json(prereq_repo)
bash = _run(_bash_cmd(prereq_repo, *args), prereq_repo)
py = _run(_py_cmd(prereq_repo, *args), prereq_repo)
assert py.returncode == bash.returncode == 0
assert py.stderr == bash.stderr == ""
assert _json_stdout(py) == _json_stdout(bash)
@requires_bash
def test_python_text_output_matches_bash(prereq_repo: Path) -> None:
feat = prereq_repo / "specs" / "001-my-feature"
feat.mkdir(parents=True)
(feat / "plan.md").write_text("# plan\n", encoding="utf-8")
(feat / "contracts").mkdir()
_write_feature_json(prereq_repo)
bash = _run(_bash_cmd(prereq_repo, "--include-tasks"), prereq_repo)
py = _run(_py_cmd(prereq_repo, "--include-tasks"), prereq_repo)
assert py.returncode == bash.returncode == 0
assert py.stderr == bash.stderr == ""
assert _normalize_status_text(py.stdout) == _normalize_status_text(bash.stdout)
@requires_bash
def test_python_help_output_matches_bash(prereq_repo: Path) -> None:
bash = _run(_bash_cmd(prereq_repo, "--help"), prereq_repo)
py = _run(_py_cmd(prereq_repo, "--help"), prereq_repo)
assert py.returncode == bash.returncode == 0
assert py.stderr == bash.stderr == ""
assert _normalize_help_text(py.stdout) == _normalize_help_text(bash.stdout)
@requires_bash
def test_python_unknown_option_matches_bash_error_shape(prereq_repo: Path) -> None:
bash = _run(_bash_cmd(prereq_repo, "--bogus"), prereq_repo)
py = _run(_py_cmd(prereq_repo, "--bogus"), prereq_repo)
assert py.returncode == bash.returncode == 1
assert py.stdout == bash.stdout == ""
assert py.stderr == bash.stderr
@pytest.mark.skipif(not (HAS_PWSH or _WINDOWS_POWERSHELL), reason="no PowerShell available")
@pytest.mark.parametrize(
("py_args", "ps_args"),
[
(("--json",), ("-Json",)),
(("--json", "--include-tasks"), ("-Json", "-IncludeTasks")),
(
("--json", "--require-tasks", "--include-tasks"),
("-Json", "-RequireTasks", "-IncludeTasks"),
),
(("--json", "--paths-only"), ("-Json", "-PathsOnly")),
],
ids=[
"json",
"json_include_tasks",
"json_require_tasks_include_tasks",
"json_paths_only",
],
)
def test_python_json_output_matches_powershell(
prereq_repo: Path, py_args: tuple[str, ...], ps_args: tuple[str, ...]
) -> None:
feat = prereq_repo / "specs" / "001-my-feature"
feat.mkdir(parents=True)
(feat / "plan.md").write_text("# plan\n", encoding="utf-8")
(feat / "tasks.md").write_text("# tasks\n", encoding="utf-8")
(feat / "research.md").write_text("# research\n", encoding="utf-8")
(feat / "data-model.md").write_text("# model\n", encoding="utf-8")
(feat / "quickstart.md").write_text("# quickstart\n", encoding="utf-8")
(feat / "contracts" / "v1").mkdir(parents=True)
_write_feature_json(prereq_repo)
ps = _run(_ps_cmd(prereq_repo, *ps_args), prereq_repo)
py = _run(_py_cmd(prereq_repo, *py_args), prereq_repo)
assert py.returncode == ps.returncode == 0
assert py.stderr == ps.stderr == ""
assert _json_stdout(py) == _json_stdout(ps)
def test_python_repo_copy_script_file_fallback_finds_repo_root(tmp_path: Path) -> None:
repo = tmp_path / "proj"
outside = tmp_path / "outside"
repo.mkdir()
outside.mkdir()
_git_init(repo)
(repo / ".specify").mkdir()
_write_feature_json(repo)
(repo / "specs" / "001-my-feature").mkdir(parents=True)
py_dir = repo / "scripts" / "python"
py_dir.mkdir(parents=True)
shutil.copy(COMMON_PY, py_dir / "common.py")
shutil.copy(CHECK_PREREQS_PY, py_dir / "check_prerequisites.py")
py = _run(_repo_copy_py_cmd(repo, "--json", "--paths-only"), outside)
assert py.returncode == 0, py.stderr
assert Path(_json_stdout(py)["REPO_ROOT"]) == repo
def test_python_paths_only_does_not_persist_feature_json(prereq_repo: Path) -> None:
(prereq_repo / "specs" / "001-my-feature").mkdir(parents=True)
(prereq_repo / "specs" / "002-other").mkdir(parents=True)
_write_feature_json(prereq_repo, "specs/001-my-feature")
feature_json = prereq_repo / ".specify" / "feature.json"
before = feature_json.read_text(encoding="utf-8")
env = _clean_env()
env["SPECIFY_FEATURE_DIRECTORY"] = "specs/002-other"
py = _run(_py_cmd(prereq_repo, "--json", "--paths-only"), prereq_repo, env=env)
assert py.returncode == 0, py.stderr
assert "002-other" in _json_stdout(py)["FEATURE_DIR"]
assert feature_json.read_text(encoding="utf-8") == before
def test_python_normal_mode_persists_feature_json(prereq_repo: Path) -> None:
(prereq_repo / "specs" / "001-my-feature").mkdir(parents=True)
feat = prereq_repo / "specs" / "002-other"
feat.mkdir(parents=True)
(feat / "plan.md").write_text("# plan\n", encoding="utf-8")
_write_feature_json(prereq_repo, "specs/001-my-feature")
env = _clean_env()
env["SPECIFY_FEATURE_DIRECTORY"] = "specs/002-other"
py = _run(_py_cmd(prereq_repo, "--json"), prereq_repo, env=env)
assert py.returncode == 0, py.stderr
data = json.loads(
(prereq_repo / ".specify" / "feature.json").read_text(encoding="utf-8")
)
assert data["feature_directory"] == "specs/002-other"
@pytest.mark.parametrize(
("args", "expected"),
[
(("--json",), "Feature directory not found"),
(("--json",), "plan.md not found"),
(("--json", "--require-tasks"), "tasks.md not found"),
],
ids=["missing_feature_context", "missing_plan", "missing_tasks"],
)
def test_python_negative_errors_are_stderr_only(
tmp_path: Path, args: tuple[str, ...], expected: str
) -> None:
repo = tmp_path / "proj"
repo.mkdir()
_git_init(repo)
(repo / ".specify").mkdir()
_install_scripts(repo)
if expected in {"plan.md not found", "tasks.md not found"}:
feat = repo / "specs" / "001-my-feature"
feat.mkdir(parents=True)
_write_feature_json(repo)
if expected == "tasks.md not found":
(feat / "plan.md").write_text("# plan\n", encoding="utf-8")
py = _run(_py_cmd(repo, *args), repo)
assert py.returncode != 0
assert expected in py.stderr
assert expected not in py.stdout
assert py.stdout.strip() == ""
def test_python_branch_falls_back_to_feature_dir_basename(prereq_repo: Path) -> None:
(prereq_repo / "specs" / "001-my-feature").mkdir(parents=True)
_write_feature_json(prereq_repo)
py = _run(_py_cmd(prereq_repo, "--json", "--paths-only"), prereq_repo)
assert py.returncode == 0, py.stderr
assert _json_stdout(py)["BRANCH"] == "001-my-feature"