zvidlib 0.4.1

Frame-accurate video and audio I/O for native and WebAssembly applications
Documentation 
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
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167

#!/usr/bin/env python3
"""Tests for `apt_install.py`.

Standard library only, and run by the `Rust checks` job with
`python3 -m unittest discover`, like the other script tests here.

What is pinned is what a CI run only shows once a mirror stalls: that every
apt-get command runs under a time limit, that a timed-out or failed attempt is
retried after recovering an interrupted install, and that the retries are
bounded so a broken install still fails the job.
"""

from __future__ import annotations

import io
import os
import tempfile
import unittest
from contextlib import redirect_stdout

import apt_install
from apt_install import TIMED_OUT, install


class FakeApt:
    """Records each command and answers it from a scripted list of statuses,
    succeeding once the list runs out."""

    def __init__(self, statuses: list[int] | None = None, mirror_list: str = "/nonexistent/apt-mirrors.txt"):
        self.mirror_list = mirror_list
        self.statuses = list(statuses or [])
        self.commands: list[list[str]] = []
        self.slept: list[float] = []

    def run(self, command):
        self.commands.append(list(command))
        if command[:2] == ["sudo", "cp"]:
            # Stand in for root writing the mirror list.
            with open(command[2]) as source, open(command[3], "w") as target:
                target.write(source.read())
            return 0
        return self.statuses.pop(0) if self.statuses else 0

    def sleep(self, seconds: float) -> None:
        self.slept.append(seconds)

    def install(self, attempts: int = 3) -> tuple[bool, str]:
        out = io.StringIO()
        with redirect_stdout(out):
            ok = install(
                ["libasound2-dev", "ffmpeg"], attempts, 240, self.run, self.sleep, self.mirror_list
            )
        return ok, out.getvalue()

    def steps(self) -> list[str]:
        """Each command reduced to its apt-get or dpkg action."""
        steps = {"update": "update", "-a": "-a"}
        return [
            "cp" if c[1] == "cp" else steps.get(c[-1], "install") for c in self.commands
        ]


class InstallTest(unittest.TestCase):
    def test_success_updates_then_installs_once(self):
        apt = FakeApt()
        ok, _ = apt.install()
        self.assertTrue(ok)
        self.assertEqual(apt.steps(), ["update", "install"])
        self.assertEqual(apt.slept, [])
        self.assertEqual(
            apt.commands[1][-4:], ["-y", "--no-install-recommends", "libasound2-dev", "ffmpeg"]
        )

    def test_every_command_runs_as_root_under_a_time_limit(self):
        apt = FakeApt([TIMED_OUT])
        apt.install()
        for command in apt.commands:
            self.assertEqual(command[:4], ["sudo", "timeout", "--kill-after=30", "240"])

    def test_apt_retries_and_gives_up_on_silent_connections(self):
        apt = FakeApt()
        apt.install()
        for command in apt.commands:
            self.assertIn("Acquire::Retries=3", command)
            self.assertIn("Acquire::http::Timeout=30", command)
            self.assertIn("DPkg::Lock::Timeout=120", command)

    def test_stalled_install_is_recovered_and_retried(self):
        apt = FakeApt([0, TIMED_OUT])
        ok, log = apt.install()
        self.assertTrue(ok)
        self.assertEqual(
            apt.steps(), ["update", "install", "-a", "update", "install"]
        )
        self.assertEqual(apt.commands[2][4:], ["dpkg", "--configure", "-a"])
        self.assertEqual(apt.slept, [10])
        self.assertIn("`apt-get install` timed out after 240 s", log)

    def test_failed_update_skips_the_install_and_retries(self):
        apt = FakeApt([100])
        ok, log = apt.install()
        self.assertTrue(ok)
        self.assertEqual(apt.steps(), ["update", "-a", "update", "install"])
        self.assertIn("`apt-get update` exited with status 100", log)

    def test_gives_up_after_the_last_attempt(self):
        apt = FakeApt([TIMED_OUT, 0, TIMED_OUT, 0, TIMED_OUT])
        ok, log = apt.install(attempts=3)
        self.assertFalse(ok)
        self.assertEqual(
            apt.steps(), ["update", "-a", "update", "-a", "update"]
        )
        self.assertEqual(apt.slept, [10, 20])
        self.assertIn("giving up after 3 attempts", log)

    def test_first_retry_drops_the_first_mirror(self):
        with tempfile.TemporaryDirectory() as directory:
            path = os.path.join(directory, "apt-mirrors.txt")
            with open(path, "w") as f:
                f.write(
                    "http://azure.archive.ubuntu.com/ubuntu/\tpriority:1\n"
                    "https://archive.ubuntu.com/ubuntu/\tpriority:2\n"
                    "https://security.ubuntu.com/ubuntu/\tpriority:3\n"
                )
            apt = FakeApt([0, TIMED_OUT, 0, 0, TIMED_OUT], mirror_list=path)
            ok, log = apt.install()
            with open(path) as f:
                mirrors = f.read()
        self.assertTrue(ok)
        self.assertEqual(
            apt.steps(),
            ["update", "install", "cp", "-a", "update", "install", "-a", "update", "install"],
        )
        self.assertEqual(
            mirrors,
            "https://archive.ubuntu.com/ubuntu/\tpriority:2\n"
            "https://security.ubuntu.com/ubuntu/\tpriority:3\n",
        )
        self.assertIn("no longer using mirror http://azure.archive.ubuntu.com/ubuntu/", log)

    def test_a_single_mirror_is_kept(self):
        with tempfile.TemporaryDirectory() as directory:
            path = os.path.join(directory, "apt-mirrors.txt")
            with open(path, "w") as f:
                f.write("https://archive.ubuntu.com/ubuntu/\tpriority:1\n")
            apt = FakeApt([TIMED_OUT], mirror_list=path)
            ok, _ = apt.install()
        self.assertTrue(ok)
        self.assertNotIn("cp", apt.steps())

    def test_main_exit_status_reflects_the_install(self):
        apt = FakeApt([1, 0, 1])
        original = apt_install.run, apt_install.time.sleep, apt_install.MIRROR_LIST
        apt_install.run, apt_install.time.sleep = apt.run, apt.sleep
        # Keep the runner's own mirror list out of reach, as on CI it exists.
        apt_install.MIRROR_LIST = apt.mirror_list
        try:
            with redirect_stdout(io.StringIO()):
                failed = apt_install.main(["--attempts", "2", "ffmpeg"])
                passed = apt_install.main(["ffmpeg"])
        finally:
            apt_install.run, apt_install.time.sleep, apt_install.MIRROR_LIST = original
        self.assertEqual((failed, passed), (1, 0))


if __name__ == "__main__":
    unittest.main()