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music-mirror/tests/test_sync_to_ipod.py
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Emma Thorpe d5dce9c769
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fix: accept a destination inside the device, and say so in --help
The script required the destination to be its own mount point, while the
documentation and its own usage text both told the user to pass
/media/IPOD/Music. The documented invocation was rejected.

A subdirectory is the better target, so the guard was what was wrong. --delete
is confined to it, and the device path budget is now derived from it -- the
part of the destination below its mount point -- rather than configured, so the
budget cannot disagree with where the files are actually going. The check that
matters is that the destination sits on a FAT filesystem, which is also what
catches an unmounted device: /media/IPOD/Music then resolves to the host's own
root filesystem, and emptying that is the outcome all of these guards exist to
prevent.

Three further faults found by testing the guards rather than reasoning about
them:

Stripping the trailing slash from "/" left an empty string, so the guard
refusing the host root never fired and the user got "destination is not a
directory" instead.

die() printed only its first argument, so the second half of the non-FAT
message -- the half saying to check whether the device is mounted -- was
silently dropped.

--help was not handled at all. Only -h reached the usage text, and it exited 2
to stderr, which is right for misuse and wrong for someone asking a question.
Help now goes to stdout and exits zero, and carries the guidance rather than
leaving it to the README, since the question it answers is asked at a terminal.

The test stage installs bash, rsync and findmnt, none of which are in the base
image, and the tests skip rather than fail where they are absent -- a machine
without rsync is not a machine that would run this script.
2026-08-25 12:23:52 +01:00

177 lines
5.4 KiB
Python

"""The guards on sync-to-ipod.sh, which are the substance of the script.
rsync --delete is being aimed at a whole filesystem, so every refusal here is
protecting against emptying the wrong directory -- a mistake that does not
announce itself.
"""
import shutil
import subprocess
from pathlib import Path
import pytest
SCRIPT = Path(__file__).resolve().parent.parent / "tools" / "sync-to-ipod.sh"
# Skipped rather than failed where the tools are absent: this is a host-side
# script, and a machine without rsync is not a machine that would run it.
REQUIRED = ("bash", "rsync", "findmnt")
pytestmark = pytest.mark.skipif(
not all(shutil.which(tool) for tool in REQUIRED),
reason=f"needs {', '.join(REQUIRED)} on PATH",
)
def run(*arguments):
return subprocess.run(
["bash", str(SCRIPT), *arguments], capture_output=True, text=True
)
@pytest.fixture
def mirror(tmp_path):
source = tmp_path / "mirror"
(source / "Album").mkdir(parents=True)
(source / "Album" / "track.mp3").write_bytes(b"x")
return source
def test_the_host_root_is_refused(mirror):
"""Stripping the trailing slash from "/" leaves an empty string, and an
earlier version then reported it as "not a directory" instead."""
result = run(str(mirror), "/")
assert result.returncode == 1
assert "refusing to sync onto /" in result.stderr
def test_an_empty_mirror_is_refused(tmp_path):
"""Mirroring nothing onto the device would delete everything on it."""
empty = tmp_path / "empty"
empty.mkdir()
destination = tmp_path / "dest"
destination.mkdir()
result = run(str(empty), str(destination))
assert result.returncode == 1
assert "refusing to mirror nothing" in result.stderr
def test_syncing_a_directory_onto_itself_is_refused(mirror):
result = run(str(mirror), str(mirror))
assert result.returncode == 1
assert "same directory" in result.stderr
def test_a_non_fat_destination_is_refused(mirror, tmp_path):
"""Which is also how an unmounted device is caught: /media/IPOD/Music then
resolves to the host's own root filesystem."""
destination = tmp_path / "dest"
destination.mkdir()
result = run(str(mirror), str(destination))
assert result.returncode == 1
assert "not FAT" in result.stderr
assert "Is the device mounted?" in result.stderr
def test_a_missing_destination_is_refused(mirror, tmp_path):
result = run(str(mirror), str(tmp_path / "nowhere"))
assert result.returncode == 1
assert "not a directory" in result.stderr
def test_a_subdirectory_of_the_device_is_a_valid_target(mirror, tmp_path):
"""The better target, in fact: --delete is confined to it."""
destination = tmp_path / "dest" / "Music"
destination.mkdir(parents=True)
result = run("-f", "-n", str(mirror), str(destination))
assert result.returncode == 0, result.stderr
assert "dry run, nothing was written" in result.stderr
def test_the_device_prefix_is_derived_from_the_destination(mirror, tmp_path):
"""Derived rather than configured, so it cannot disagree with where the
files are actually going -- and the device's path limit applies to it."""
destination = tmp_path / "dest" / "Music"
destination.mkdir(parents=True)
result = run("-f", "-n", str(mirror), str(destination))
assert "the device will see this as /" in result.stderr
def test_a_dry_run_writes_nothing(mirror, tmp_path):
destination = tmp_path / "dest"
destination.mkdir()
run("-f", "-n", str(mirror), str(destination))
assert list(destination.iterdir()) == []
def test_rockbox_is_never_deleted(mirror, tmp_path):
"""A sync to the card root would otherwise remove the Rockbox install,
since the mirror does not contain it."""
destination = tmp_path / "dest"
destination.mkdir()
(destination / ".rockbox").mkdir()
(destination / ".rockbox" / "rockbox.ipod").write_bytes(b"firmware")
(destination / ".scrobbler.log").write_bytes(b"#AUDIOSCROBBLER/1.1\n")
(destination / "Stale.mp3").write_bytes(b"old")
result = run("-f", "-S", "-U", str(mirror), str(destination))
assert result.returncode == 0, result.stderr
assert (destination / ".rockbox" / "rockbox.ipod").is_file()
assert (destination / ".scrobbler.log").is_file()
# But a track whose source has gone is still removed. That is the point.
assert not (destination / "Stale.mp3").exists()
assert (destination / "Album" / "track.mp3").is_file()
def test_help_goes_to_stdout_and_exits_clean():
"""Asking for help is not an error; getting the arguments wrong is."""
result = run("--help")
assert result.returncode == 0
assert result.stdout.startswith("usage:")
assert result.stderr == ""
def test_short_help_behaves_the_same():
result = run("-h")
assert result.returncode == 0
assert result.stdout.startswith("usage:")
def test_misuse_goes_to_stderr_and_does_not():
result = run("only-one-argument")
assert result.returncode == 2
assert result.stderr.startswith("usage:")
assert result.stdout == ""
def test_the_help_explains_what_the_destination_should_be():
"""The question this script actually gets asked."""
help_text = run("--help").stdout
assert "/media/IPOD/Music" in help_text
assert "artist folders" in help_text
assert ".rockbox" in help_text
def test_the_help_says_how_to_reach_and_leave_disk_mode():
help_text = run("--help").stdout
assert "Menu+Select" in help_text
assert "holding Play" in help_text