MusicFS/docs/e2e-test-plan.md

beetfs E2E Test Plan

Reviewed by Oracle - Critical bug discovered, plan updated accordingly

Test Results (Latest Run)

Tests run:   74
Passed:      12
Failures:    56
Errors:       3
Skipped:      3
Duration:    ~103 seconds

Bugs Detected by Tests

Bug	Tests Affected	Description
Nested Methods	56	Lines 758-1144 indented inside access() - FUSE operations unreachable
Directory Tree Building	3	KeyError in FSNode.getnode() when adding files
Unmount	1	Filesystem not unmounting cleanly

Passing Tests (12)

• test_fuse_available - FUSE/fusermount detected
• test_library_fixture_created - SQLite DB and music dir created
• test_temp_directory_created - Temp dirs set up correctly
• test_mount_empty_library - Mount works with empty library!
• test_list_empty_root - Empty root returns empty list
• test_list_root_returns_list - Returns list type
• test_access_empty_path - Handles empty path
• Plus 5 nested bug detection tests (confirming bug exists)

Executive Summary

E2E tests for beetfs FUSE filesystem using real music files from qBittorrent container. No mocks - actual filesystem operations against mounted beetfs.

Critical Finding

BUG DISCOVERED: Lines 758-1144 in beetFs.py are indented inside access() method, making these FUSE operations unreachable as class methods:

• readdir, open, read, write, mkdir, unlink, rmdir, symlink, link, rename, chmod, chown, truncate, opendir, releasedir, fsyncdir, create, fgetattr, release, fsync, flush, ftruncate

Tests will expose this immediately - write test_readdir.py first.

---

Test Environment

Component	Status	Details
Real Music	Available	Metallica "72 Seasons" (12 FLAC, 650MB) at /home/fujin/.local/share/docker/volumes/containers_downloads/_data/Metallica - 72 Seasons (2023) [FLAC] 88/
Synthetic Music	Create	5-10MB FLACs for most tests (avoid RAM explosion)
Beets Config	Create	~/.config/beets/config.yaml for test isolation
Beets Library	Empty	Needs import of test files
Python	2.7.15	Via Nix flake (nixpkgs-18.09)
Test Framework	unittest	stdlib, no external deps for Py2.7

---

Test Architecture

beetfs/tests/
├── __init__.py
├── conftest.py              # Test fixtures, beets library setup, synthetic FLAC creation
├── test_smoke.py            # Mount/unmount lifecycle (run FIRST)
├── test_nested_bug.py       # Verify the indentation bug (run SECOND)
├── test_readdir.py          # Directory listing operations
├── test_read.py             # File reading with metadata overlay (CORE FEATURE)
├── test_stat.py             # getattr, fgetattr, statfs
├── test_write.py            # Metadata write operations
├── test_error_handling.py   # ENOENT, EOPNOTSUPP scenarios
├── test_edge_cases.py       # Unicode, concurrent opens, special chars
├── test_integration.py      # Real 650MB files (skip by default)
└── fixtures/
    ├── synthetic/           # Generated 5-10MB test FLACs
    └── real -> /home/fujin/.local/share/docker/volumes/containers_downloads/_data/

---

Test Tiers

Tier 1: Unit-ish (Synthetic FLACs, ~500KB each)

• Fast execution
• No memory issues (FileHandler loads entire file to RAM)
• Run on every commit

Tier 2: Integration (Subset of real files, 1-2 tracks)

• Uses real Metallica FLACs
• Tests real-world metadata
• Run before merge

Tier 3: E2E (All 12 tracks, 650MB)

• Full album processing
• Memory stress testing
• Run via E2E=1 python -m unittest discover
• Skip by default

---

Test Isolation Strategy

Resource	Strategy	Rationale
Audio Files	Symlinks for reads	beetfs NEVER writes to source files, only to beets DB
Beets DB	Copy per test	Writes mutate DB; need isolation
Mount Point	Fresh tempdir	Each test gets clean mount
Global State	Fresh subprocess	library, directory_structure are module globals

---

Implementation Order

Reordered per Oracle recommendation: smoke → nested-bug → read → write → errors → edge

Phase 1: Infrastructure (Day 1 AM)

1. Create tests/ directory structure
2. Implement BeetFSTestCase base class with:
   • Subprocess timeout via threading.Timer (Py2.7 compatible)
   • Mount wait polling (os.path.ismount())
   • Proper cleanup (fusermount -u)
3. Create synthetic FLAC generator using ffmpeg + flac CLI
4. Setup isolated beets config and library

Phase 2: Bug Detection (Day 1 PM)

5. test_smoke.py - Mount/unmount lifecycle
6. test_nested_bug.py - Verify readdir, open are callable (will fail, exposing bug)

Phase 3: Core Tests (Day 2)

7. test_readdir.py - Directory listing
8. test_read.py - Metadata overlay verification (critical)
9. test_stat.py - File/directory attributes

Phase 4: Write & Errors (Day 3)

10. test_write.py - Metadata modification, DB persistence
11. test_error_handling.py - ENOENT, EOPNOTSUPP

Phase 5: Edge Cases (Day 3-4)

12. test_edge_cases.py - Unicode, concurrent opens, special chars
13. test_integration.py - Real 650MB files (optional tier)

---

Test Categories

1. Smoke Tests (test_smoke.py)

Test	Operation	Expected
test_mount_success	Mount beetfs	os.path.ismount() returns True
test_unmount_clean	Unmount	Process exits 0, dir accessible
test_mount_empty_library	Mount with 0 items	Mounts successfully, root empty
test_mount_invalid_path	Mount to non-existent	Fails gracefully
test_fsinit_called	Check initialization	No crash on mount

2. Nested Methods Bug (test_nested_bug.py)

Test	Operation	Expected
test_readdir_exists	hasattr(beetFileSystem, 'readdir')	True (currently False!)
test_open_exists	hasattr(beetFileSystem, 'open')	True (currently False!)
test_read_exists	hasattr(beetFileSystem, 'read')	True (currently False!)
test_readdir_callable	os.listdir(mount)	Returns list (currently fails!)

3. Directory Operations (test_readdir.py)

Test	Operation	Expected
test_list_root	os.listdir(mount)	Returns artist directories
test_list_artist	os.listdir(mount/artist)	Returns album directories
test_list_album	os.listdir(mount/artist/album)	Returns track files
test_path_format	Check structure	Matches $artist/$album ($year) [$format_upper]/$track - $artist - $title.$format
test_unicode_paths	Non-ASCII chars	Handles "Lux Aeterna" correctly

4. Read Operations (test_read.py) - CORE FEATURE

Test	Operation	Expected
test_read_header_overlay	Read + parse with mutagen	Tags match DB, not file
test_read_audio_passthrough	Compare audio bytes	Identical to original after header
test_read_full_file	Read entire file	Header from DB + audio from file
test_metadata_artist	Check artist tag	DB value, not file value
test_metadata_title	Check title tag	DB value, not file value
test_metadata_album	Check album tag	DB value, not file value
test_metadata_genre	Check genre tag	DB value, not file value
test_original_unchanged	Read original file	Original metadata intact

Metadata Overlay Verification Pattern

import mutagen.flac
from io import BytesIO

def test_read_header_overlay(self):
    # Setup: Import file, modify DB metadata
    # beet import /path/to/file
    # beet modify artist="DB Artist"  # File has "Original Artist"
    
    # Read mounted file as bytes
    with open(os.path.join(self.mount_dir, 'DB Artist/...'), 'rb') as f:
        mounted_data = f.read()
    
    # Parse with mutagen
    flac = mutagen.flac.FLAC(BytesIO(mounted_data))
    
    # Verify overlay worked
    self.assertEqual(flac['artist'][0], 'DB Artist')  # From DB
    self.assertNotEqual(flac['artist'][0], 'Original Artist')  # Not from file

5. Stat Operations (test_stat.py)

Test	Operation	Expected
test_stat_file	os.stat(file)	Valid stat with size, mtime
test_stat_directory	os.stat(dir)	Directory mode (S_IFDIR)
test_statfs	os.statvfs(mount)	Valid filesystem stats
test_access_read	os.access(file, R_OK)	True
test_access_write	os.access(file, W_OK)	True (header writable)

6. Write Operations (test_write.py)

Test	Operation	Expected
test_write_title	Modify title in header	DB updated, file unchanged
test_write_artist	Modify artist	DB updated
test_write_album	Modify album	DB updated
test_write_genre	Modify genre	DB updated
test_write_audio_discarded	Write at offset > bound	Silently discarded
test_write_persistence	Write -> unmount -> remount	Changes persisted in DB
test_write_mp3_noop	Write to MP3 header	No error, but no effect (bound=0)

7. Error Handling (test_error_handling.py)

Test	Operation	Expected
test_enoent_file	Read non-existent	OSError(ENOENT)
test_enoent_dir	List non-existent	OSError(ENOENT)
test_eopnotsupp_mkdir	os.mkdir()	OSError(EOPNOTSUPP)
test_eopnotsupp_unlink	os.unlink()	OSError(EOPNOTSUPP)
test_eopnotsupp_rename	os.rename()	OSError(EOPNOTSUPP)
test_eopnotsupp_symlink	os.symlink()	OSError(EOPNOTSUPP)

8. Edge Cases (test_edge_cases.py)

Test	Operation	Expected
test_special_chars_sanitized	Path with ?/	Sanitized via sanitize()
test_concurrent_opens	Open same file twice	instance_count increments
test_concurrent_release	Release after double open	File stays cached until count=0
test_unicode_metadata	Non-ASCII in artist/title	Handled correctly
test_empty_metadata	None/empty fields	Doesn't crash
test_mp3_no_interpolation	Read MP3	Returns original file (no overlay)

9. Integration (test_integration.py)

Test	Env Var	Expected
test_real_album_listing	E2E=1	Lists all 12 Metallica tracks
test_real_file_read	E2E=1	Reads 67MB file successfully
test_memory_usage	E2E=1	Documents but doesn't fail on high RAM

---

Test Infrastructure Code

Base Test Class (Python 2.7 Compatible)

# tests/conftest.py
import unittest
import subprocess
import tempfile
import shutil
import os
import time
import threading

class BeetFSTestCase(unittest.TestCase):
    """Base class for beetfs e2e tests - Python 2.7 compatible"""
    
    MOUNT_TIMEOUT = 30  # seconds
    
    @classmethod
    def setUpClass(cls):
        """Check FUSE availability"""
        try:
            with open(os.devnull, 'w') as devnull:
                subprocess.check_call(['which', 'fusermount'], 
                                     stdout=devnull, stderr=devnull)
        except subprocess.CalledProcessError:
            raise unittest.SkipTest("fusermount not available")
    
    def setUp(self):
        self.mount_dir = tempfile.mkdtemp(prefix='beetfs_test_')
        self.fs_process = None
    
    def mount_beetfs(self, library_path=None):
        """Mount beetfs in background with timeout"""
        cmd = ['python', '-c', 
               'from beetsplug.beetFs import mount; mount()']
        # Add mount point and other args as needed
        
        self.fs_process = subprocess.Popen(
            cmd,
            stdout=open(os.devnull, 'w'),
            stderr=subprocess.STDOUT
        )
        
        # Python 2.7 timeout workaround
        timer = threading.Timer(self.MOUNT_TIMEOUT, self._timeout_kill)
        timer.start()
        
        try:
            self._wait_for_mount()
        finally:
            timer.cancel()
    
    def _timeout_kill(self):
        if self.fs_process and self.fs_process.poll() is None:
            self.fs_process.kill()
    
    def _wait_for_mount(self):
        """Wait for filesystem to be mounted"""
        start = time.time()
        while time.time() - start < self.MOUNT_TIMEOUT:
            if os.path.ismount(self.mount_dir):
                return
            if self.fs_process.poll() is not None:
                self.fail("Filesystem process terminated prematurely")
            time.sleep(0.1)
        self.fail("Mount timeout after {} seconds".format(self.MOUNT_TIMEOUT))
    
    def tearDown(self):
        """Cleanup: unmount and kill process"""
        if self.fs_process:
            with open(os.devnull, 'w') as devnull:
                subprocess.call(['fusermount', '-z', '-u', self.mount_dir],
                              stdout=devnull, stderr=devnull)
            
            self.fs_process.terminate()
            
            # Wait for termination (Py2.7 compatible)
            start = time.time()
            while time.time() - start < 5:
                if self.fs_process.poll() is not None:
                    break
                time.sleep(0.1)
            else:
                self.fs_process.kill()
        
        shutil.rmtree(self.mount_dir, ignore_errors=True)

Synthetic FLAC Generator

# tests/conftest.py (continued)
import subprocess
import tempfile
import os

def create_synthetic_flac(duration_sec=5, artist="Test Artist", 
                          title="Test Track", album="Test Album"):
    """Create minimal FLAC with known metadata (~500KB for 5s silence)"""
    wav_fd, wav_path = tempfile.mkstemp(suffix='.wav')
    os.close(wav_fd)
    flac_path = wav_path.replace('.wav', '.flac')
    
    try:
        # Generate silence WAV
        subprocess.check_call([
            'ffmpeg', '-f', 'lavfi', '-i', 
            'anullsrc=r=44100:cl=stereo', '-t', str(duration_sec),
            '-y', wav_path
        ], stdout=open(os.devnull, 'w'), stderr=subprocess.STDOUT)
        
        # Convert to FLAC with metadata
        subprocess.check_call([
            'flac', '--best', 
            '-T', 'ARTIST={}'.format(artist),
            '-T', 'TITLE={}'.format(title),
            '-T', 'ALBUM={}'.format(album),
            '-o', flac_path, wav_path
        ], stdout=open(os.devnull, 'w'), stderr=subprocess.STDOUT)
        
        return flac_path
    finally:
        if os.path.exists(wav_path):
            os.unlink(wav_path)

---

Dependencies to Add to flake.nix

# In devShell buildInputs, add:
pkgs.ffmpeg    # For synthetic FLAC generation
pkgs.flac      # For FLAC encoding

# pythonEnv already has mutagen for verification

---

Risks & Mitigations

Risk	Impact	Mitigation
Memory explosion	High	Use 5-10MB synthetic FLACs, skip 650MB tests by default
Nested methods bug	Critical	Tests will expose; fix required before other tests pass
Python 2.7 EOL	Medium	Nix provides isolated environment
Global state pollution	Medium	Fresh subprocess per test
FUSE permissions	Low	Run as regular user, skip privileged tests
Concurrent access	Low	Single-threaded mode, sequential tests

---

Success Criteria

1. All smoke tests pass - beetfs mounts and unmounts cleanly
2. Nested bug exposed and fixed - All FUSE methods callable
3. Metadata overlay verified - Reads return DB metadata, not file metadata
4. Writes update DB - Metadata changes persist
5. Errors handled gracefully - Correct errno for unsupported ops
6. No crashes on edge cases - Unicode, special chars, concurrent access

---

Findings from Test Execution

Bug #1: Nested Methods (CRITICAL)

Location: beetFs.py lines 758-1144

Problem: All FUSE operation methods are indented inside the access() method, making them local functions instead of class methods.

Evidence:

def access(self, path, flags):   # Line 723 - correct class method
    ...
    return 0

    def readdir(self, path, ...):  # Line 931 - WRONG! Nested inside access()
        ...
    def open(self, path, flags):   # Line 988 - Also nested
        ...
    def read(self, path, ...):     # Line 1077 - Also nested
        ...

Symptom: os.listdir() returns OSError: [Errno 38] Function not implemented

Fix Required: Dedent lines 758-1144 by 8 spaces to make them class methods.

Bug #2: Directory Tree Building

Location: beetFs.py lines 403-414 (FSNode.getnode() and FSNode.adddir())

Problem: When adding files to the directory structure, the code assumes parent directories already exist.

Evidence:

KeyError: u'Test Artist'
File "beetFs.py", line 403, in getnode
    return self.getnode(elements, root=root.dirs[topdir])

Symptom: Mount fails when library contains tracks.

Bug #3: Unmount Not Clean

Problem: After unmounting, os.path.ismount() still returns True.

Likely Cause: FUSE process not terminating properly, or lazy unmount not completing.

---

Notes from Oracle Review

1. MP3 is not "readonly" - metadata overlay is disabled (bound=0), but reads still work
2. Write returns None for MP3 - no explicit return in MP3 path (falls through)
3. Path format is hardcoded - tests must match $artist/$album ($year) [$format_upper]/$track - $artist - $title.$format
4. basestring vs str - use isinstance(x, basestring) for Py2.7 string checks
5. Global variables - library, directory_structure must be reset between tests (use subprocesses)