PICARD-2897: Try to guess format for files with unknown extension

Author: phw

picard/formats/util.py

@@ -77,8 +77,9 @@ def open_(filename):
             ext = filename[i+1:].lower()
             file_format = ext_to_format(ext)
             if file_format is None:
-                return None
-            audio_file = file_format(filename)
+                audio_file = guess_format(filename)
+            else:
+                audio_file = file_format(filename)
         else:
             # If there is no extension, try to guess the format based on file headers
             audio_file = guess_format(filename)

test/formats/test_util.py

@@ -0,0 +1,56 @@
+# -*- coding: utf-8 -*-
+#
+# Picard, the next-generation MusicBrainz tagger
+#
+# Copyright (C) 2024 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 os.path
+
+from test.picardtestcase import PicardTestCase
+
+from picard.formats import util
+from picard.formats.id3 import MP3File
+
+
+class FormatsOpenTest(PicardTestCase):
+    def setUp(self):
+        super().setUp()
+        self.set_config_values({'enabled_plugins': []})
+
+    def test_open(self):
+        file_path = os.path.join('test', 'data', 'test.mp3')
+        filename = self.copy_file_tmp(file_path, '.mp3')
+        filetype = util.open_(filename)
+        self.assertIsInstance(filetype, MP3File)
+
+    def test_open_no_extension(self):
+        file_path = os.path.join('test', 'data', 'test.mp3')
+        filename = self.copy_file_tmp(file_path, '')
+        filetype = util.open_(filename)
+        self.assertIsInstance(filetype, MP3File)
+
+    def test_open_unknown_extension(self):
+        file_path = os.path.join('test', 'data', 'test.mp3')
+        filename = self.copy_file_tmp(file_path, '.fake')
+        filetype = util.open_(filename)
+        self.assertIsInstance(filetype, MP3File)
+
+    def test_open_unknown_type(self):
+        file_path = os.path.join('test', 'data', 'mb.png')
+        filename = self.copy_file_tmp(file_path, '.ogg')
+        filetype = util.open_(filename)
+        self.assertIsNone(filetype)