lint: check file extension for metadata

This helps keep fdroiddata clean, on @krt's request.

closes #222

tests/lint.TestCase

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+
+# http://www.drdobbs.com/testing/unit-testing-with-python/240165163
+
+import inspect
+import optparse
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+
+localmodule = os.path.realpath(
+    os.path.join(os.path.dirname(inspect.getfile(inspect.currentframe())), '..'))
+print('localmodule: ' + localmodule)
+if localmodule not in sys.path:
+    sys.path.insert(0, localmodule)
+
+import fdroidserver.common
+import fdroidserver.lint
+
+
+class LintTest(unittest.TestCase):
+    '''fdroidserver/lint.py'''
+
+    def test_check_for_unsupported_metadata_files(self):
+        config = dict()
+        fdroidserver.common.fill_config_defaults(config)
+        config['accepted_formats'] = ('txt', 'yml')
+        fdroidserver.common.config = config
+        fdroidserver.lint.config = config
+        self.assertTrue(fdroidserver.lint.check_for_unsupported_metadata_files())
+
+        tmpdir = os.path.join(localmodule, '.testfiles')
+        tmptestsdir = tempfile.mkdtemp(prefix='test_check_for_unsupported_metadata_files-',
+                                       dir=tmpdir)
+        self.assertFalse(fdroidserver.lint.check_for_unsupported_metadata_files(tmptestsdir + '/'))
+        shutil.copytree(os.path.join(localmodule, 'tests', 'metadata'),
+                        os.path.join(tmptestsdir, 'metadata'),
+                        ignore=shutil.ignore_patterns('apk', 'dump', '*.json'))
+        self.assertFalse(fdroidserver.lint.check_for_unsupported_metadata_files(tmptestsdir + '/'))
+        shutil.copy(os.path.join(localmodule, 'tests', 'metadata', 'org.adaway.json'),
+                    os.path.join(tmptestsdir, 'metadata'))
+        self.assertTrue(fdroidserver.lint.check_for_unsupported_metadata_files(tmptestsdir + '/'))
+
+
+if __name__ == "__main__":
+    parser = optparse.OptionParser()
+    parser.add_option("-v", "--verbose", action="store_true", default=False,
+                      help="Spew out even more information than normal")
+    (fdroidserver.lint.options, args) = parser.parse_args(['--verbose'])
+    fdroidserver.common.options = fdroidserver.lint.options
+
+    newSuite = unittest.TestSuite()
+    newSuite.addTest(unittest.makeSuite(LintTest))
+    unittest.main()