PICARD-1807: Fix error handling when using python-libdiscid

discid.disc.DiscError only exists in python-discid, not in the compat version of python-libdiscid. The proper way in both libraries is to access discid.DiscError.

test/test_disc.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+#
+# Picard, the next-generation MusicBrainz tagger
+#
+# Copyright (C) 2020 Philipp Wolfer
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+import unittest
+
+from test.picardtestcase import PicardTestCase
+
+import picard.disc
+
+
+class DiscTest(PicardTestCase):
+    @unittest.skipUnless(picard.disc.discid, "discid not available")
+    def test_raise_disc_error(self):
+        disc = picard.disc.Disc()
+        self.assertRaises(picard.disc.discid.DiscError, disc.read, 'notadevice')