Move DOS/MBR check into the testsuite.

debian/rules

@@ -41,9 +41,6 @@ debian/diffoscope.bash-completion:
 	register-python-argcomplete diffoscope > $@
 
 override_dh_auto_build: debian/diffoscope.bash-completion
-	@# Let's avoid plonking everything in the "DOS/MBR" category, this is really not
-	@# a sustainable filetype testing solution (e.g. c051ba9d and c1442405).
-	! grep 'DOS/MBR' -R diffoscope
 	dh_auto_build -O--buildsystem=pybuild
 	dh_auto_build -O--buildsystem=makefile -Ddoc
 

tests/test_source.py

+# -*- coding: utf-8 -*-
+#
+# diffoscope: in-depth comparison of files, archives, and directories
+#
+# Copyright © 2018 Chris Lamb <lamby@debian.org>
+#
+# diffoscope 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 3 of the License, or
+# (at your option) any later version.
+#
+# diffoscope 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 diffoscope.  If not, see <https://www.gnu.org/licenses/>.
+
+import os
+import glob
+import pytest
+import diffoscope
+
+BASE_DIR = os.path.dirname(os.path.abspath(diffoscope.__file__))
+
+
+def test_dos_mbr():
+    for x in glob.iglob(os.path.join(BASE_DIR, '**', '*.py'), recursive=True):
+        assert 'DOS/MBR' not in open(x).read()