1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
|
import os
import json
import subprocess
from typing import Any
from pathlib import Path
import dataclasses
@dataclasses.dataclass
class CommandResult:
cmd: list[str]
rc: int
"""Return code"""
stderr: bytes
"""Outputted stderr"""
stdout: bytes
"""Outputted stdout"""
def ok(self):
if self.rc != 0:
raise subprocess.CalledProcessError(returncode=self.rc,
cmd=self.cmd,
stderr=self.stderr,
output=self.stdout)
return self
def json(self) -> Any:
self.ok()
return json.loads(self.stdout)
@dataclasses.dataclass
class NixSettings:
"""Settings for invoking Nix"""
experimental_features: set[str] | None = None
def feature(self, *names: str):
self.experimental_features = (self.experimental_features
or set()) | set(names)
return self
def to_config(self) -> str:
config = ''
def serialise(value):
if type(value) in {str, int}:
return str(value)
elif type(value) in {list, set}:
return ' '.join(str(e) for e in value)
else:
raise ValueError(
f'Value is unsupported in nix config: {value!r}')
def field_may(name, value, serialiser=serialise):
nonlocal config
if value is not None:
config += f'{name} = {serialiser(value)}\n'
field_may('experimental-features', self.experimental_features)
return config
@dataclasses.dataclass
class Nix:
test_root: Path
def hermetic_env(self):
# mirroring vars-and-functions.sh
home = self.test_root / 'test-home'
home.mkdir(parents=True, exist_ok=True)
return {
'NIX_STORE_DIR': self.test_root / 'store',
'NIX_LOCALSTATE_DIR': self.test_root / 'var',
'NIX_LOG_DIR': self.test_root / 'var/log/nix',
'NIX_STATE_DIR': self.test_root / 'var/nix',
'NIX_CONF_DIR': self.test_root / 'etc',
'NIX_DAEMON_SOCKET_PATH': self.test_root / 'daemon-socket',
'NIX_USER_CONF_FILES': '',
'HOME': home,
}
def make_env(self):
# We conservatively assume that people might want to successfully get
# some env through to the subprocess, so we override whatever is in the
# global env.
d = os.environ.copy()
d.update(self.hermetic_env())
return d
def call(self, cmd: list[str], extra_env: dict[str, str] = {}):
"""
Calls a process in the test environment.
"""
env = self.make_env()
env.update(extra_env)
proc = subprocess.Popen(
cmd,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
cwd=self.test_root,
env=env,
)
(stdout, stderr) = proc.communicate()
rc = proc.returncode
return CommandResult(cmd=cmd, rc=rc, stdout=stdout, stderr=stderr)
def nix(self,
cmd: list[str],
settings: NixSettings = NixSettings(),
extra_env: dict[str, str] = {}):
extra_env = extra_env.copy()
extra_env.update({'NIX_CONFIG': settings.to_config()})
return self.call(['nix', *cmd], extra_env)
def eval(
self, expr: str,
settings: NixSettings = NixSettings()) -> CommandResult:
# clone due to reference-shenanigans
settings = dataclasses.replace(settings).feature('nix-command')
return self.nix(['eval', '--json', '--expr', expr], settings=settings)
|
