122 lines
3.7 KiB
Python
122 lines
3.7 KiB
Python
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import os
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import json
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import subprocess
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from typing import Any
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from pathlib import Path
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import dataclasses
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@dataclasses.dataclass
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class CommandResult:
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cmd: list[str]
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rc: int
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"""Return code"""
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stderr: bytes
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"""Outputted stderr"""
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stdout: bytes
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"""Outputted stdout"""
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def ok(self):
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if self.rc != 0:
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raise subprocess.CalledProcessError(returncode=self.rc,
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cmd=self.cmd,
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stderr=self.stderr,
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output=self.stdout)
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return self
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def json(self) -> Any:
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self.ok()
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return json.loads(self.stdout)
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@dataclasses.dataclass
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class NixSettings:
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"""Settings for invoking Nix"""
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experimental_features: set[str] | None = None
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def feature(self, *names: str):
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self.experimental_features = (self.experimental_features
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or set()) | set(names)
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return self
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def to_config(self) -> str:
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config = ''
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def serialise(value):
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if type(value) in {str, int}:
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return str(value)
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elif type(value) in {list, set}:
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return ' '.join(str(e) for e in value)
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else:
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raise ValueError(
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f'Value is unsupported in nix config: {value!r}')
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def field_may(name, value, serialiser=serialise):
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nonlocal config
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if value is not None:
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config += f'{name} = {serialiser(value)}\n'
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field_may('experimental-features', self.experimental_features)
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return config
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@dataclasses.dataclass
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class Nix:
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test_root: Path
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def hermetic_env(self):
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# mirroring vars-and-functions.sh
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home = self.test_root / 'test-home'
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home.mkdir(parents=True, exist_ok=True)
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return {
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'NIX_STORE_DIR': self.test_root / 'store',
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'NIX_LOCALSTATE_DIR': self.test_root / 'var',
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'NIX_LOG_DIR': self.test_root / 'var/log/nix',
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'NIX_STATE_DIR': self.test_root / 'var/nix',
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'NIX_CONF_DIR': self.test_root / 'etc',
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'NIX_DAEMON_SOCKET_PATH': self.test_root / 'daemon-socket',
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'NIX_USER_CONF_FILES': '',
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'HOME': home,
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}
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def make_env(self):
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# We conservatively assume that people might want to successfully get
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# some env through to the subprocess, so we override whatever is in the
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# global env.
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d = os.environ.copy()
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d.update(self.hermetic_env())
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return d
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def call(self, cmd: list[str], extra_env: dict[str, str] = {}):
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"""
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Calls a process in the test environment.
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"""
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env = self.make_env()
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env.update(extra_env)
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proc = subprocess.Popen(
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cmd,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE,
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cwd=self.test_root,
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env=env,
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)
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(stdout, stderr) = proc.communicate()
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rc = proc.returncode
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return CommandResult(cmd=cmd, rc=rc, stdout=stdout, stderr=stderr)
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def nix(self,
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cmd: list[str],
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settings: NixSettings = NixSettings(),
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extra_env: dict[str, str] = {}):
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extra_env = extra_env.copy()
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extra_env.update({'NIX_CONFIG': settings.to_config()})
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return self.call(['nix', *cmd], extra_env)
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def eval(
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self, expr: str,
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settings: NixSettings = NixSettings()) -> CommandResult:
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# clone due to reference-shenanigans
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settings = dataclasses.replace(settings).feature('nix-command')
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return self.nix(['eval', '--json', '--expr', expr], settings=settings)
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