Test failure with mutagen >= 1.33

[bjornfor]

Problem

(Sorry for skipping the issue template, but it seemed aimed at different kind of issues. I think this is a good format for humans.)

When building beets against mutagen >= 1.33 (tested 1.33 and 1.34 (latest)), the following test failure happens:

test_no_patterns (test.test_zero.ZeroPluginTest) ... ok
test_patterns (test.test_zero.ZeroPluginTest) ... ok

======================================================================
ERROR: test_broken_symlink (test.test_mediafile_edge.SafetyTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/test/test_mediafile_edge.py", line 196, in test_broken_symlink
    beets.mediafile.MediaFile, fn)
  File "/nix/store/3wl86vswinz1cam7jmzdvvaglg2566l6-python-2.7.12/lib/python2.7/unittest/case.py", line 473, in assertRaises
    callableObj(*args, **kwargs)
  File "/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/beets/mediafile.py", line 1377, in __init__
    raise MutagenError(path, exc)
MutagenError: /tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/test/rsrc/brokenlink: [Errno 2] No such file or directory: '/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/test/rsrc/brokenlink'
-------------------- >> begin captured logging << --------------------
beets: DEBUG: Traceback (most recent call last):
  File "/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/beets/mediafile.py", line 1361, in __init__
    self.mgfile = mutagen.File(path)
  File "/nix/store/qiac3k1wcr69mfcmlczkxcj5fa0p4bp7-python2.7-mutagen-1.33/lib/python2.7/site-packages/mutagen/_util.py", line 105, in wrapper_func
    writable, create) as h:
  File "/nix/store/3wl86vswinz1cam7jmzdvvaglg2566l6-python-2.7.12/lib/python2.7/contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "/nix/store/qiac3k1wcr69mfcmlczkxcj5fa0p4bp7-python2.7-mutagen-1.33/lib/python2.7/site-packages/mutagen/_util.py", line 192, in _openfile
    raise MutagenError(e)
MutagenError: [Errno 2] No such file or directory: '/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/test/rsrc/brokenlink'

beets: ERROR: uncaught Mutagen exception in open: [Errno 2] No such file or directory: '/tmp/nix-build-beets-1.3.19.drv-0/beets-v1.3.19-src/test/rsrc/brokenlink'
--------------------- >> end captured logging << ---------------------

----------------------------------------------------------------------
Ran 1682 tests in 68.862s

FAILED (SKIP=21, errors=1)
builder for ‘/nix/store/139y94l5a6zg78q8nymfzld36vninhh5-beets-1.3.19.drv’ failed with exit code 1
error: build of ‘/nix/store/139y94l5a6zg78q8nymfzld36vninhh5-beets-1.3.19.drv’ failed

I guess this is easily "solveable" by restricting the mutagen version spec in setup.py (currently 'mutagen>=1.27'). But as someone who is involved with distro packaging (NixOS) I kindly ask if you can try to be compatible with the new version instead. (Strict version requirements makes packaging difficult.)

[sampsyo]

Interesting! Thanks for the report. I can't reproduce this here—we do indeed regularly test with the latest Mutagen. You can see the versions at the top of the CI log here: https://travis-ci.org/beetbox/beets/jobs/149035232

Is there any chance this might be Nix-specific? Or that you've got an older version of the source? In particular, that raise MutagenError line is inside a handler that should have caught the IOError you're seeing there separately.

[sampsyo]

It looks like something may have gotten out of sync with the exception hierarchy rework in this commit: 629241e

There are some other problems here that I will try addressing now. I'll likely end up requiring Mutagen >= 1.33. When that's done, can you give things a try again to see if you still see the problem?

[bjornfor]

@sampsyo: I forgot to say that this is with beets 1.3.19 (latest release). (Although that can be seen in the build log.) In your build log I see beets 1.4.0, which is still unreleased, as far as I can tell.

When that's done, can you give things a try again to see if you still see the problem?

Sure. But I'm kind of busy for the next three weeks, I'll see what I can do. If you manage to reproduce the error with beets 1.3.19 and mutagen 1.33/34, that'd be great. This issue is three steps off my road towards a goal. Yak shaving... :-)

[sampsyo]

Ah, got it. Here's the problem: when beets 1.3.19 was released, Mutagen 1.33 didn't exist yet. When that was released, it changed the way exceptions work, which broke those tests. We've since fixed compatibility with the latest version, but we can't go back in time and change the version specifier for 1.3.19.

But the 1.4.0 release should be right around the corner, so this should all be over soon. Back to shaving other yaks. 😃

[bjornfor]

@sampsyo: Thank you!