Add unit test for BugManager._guess_packages to cover an arbitrary subject value

tests/unit/bugs/test_bugs.py

+#   test_bugs.py - Test debexpo Bug model
+#
+#   This file is part of debexpo
+#   https://salsa.debian.org/mentors.debian.net-team/debexpo
+#
+#   Copyright © 2022 Baptiste Beauplat <lyknode@debian.org>
+#
+#   Permission is hereby granted, free of charge, to any person
+#   obtaining a copy of this software and associated documentation
+#   files (the "Software"), to deal in the Software without
+#   restriction, including without limitation the rights to use,
+#   copy, modify, merge, publish, distribute, sublicense, and/or sell
+#   copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following
+#   conditions:
+#
+#   The above copyright notice and this permission notice shall be
+#   included in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+#   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+#   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+#   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+#   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+#   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+#   OTHER DEALINGS IN THE SOFTWARE.
+
+from tests import TestController
+
+from debexpo.bugs.models import Bug
+
+
+class TestBugs(TestController):
+    def test_guess_packages(self):
+        # Normal bug
+        packages = Bug.objects._guess_packages(
+            'package1',
+            'FTBFS: with foo from experimental'
+        )
+
+        self.assertEquals(len(packages), 1)
+        self.assertEquals(packages[0].name, 'package1')
+
+        # Bug linked to multiple packages
+        packages = Bug.objects._guess_packages(
+            'package1,package2',
+            'FTBFS: with foo from experimental'
+        )
+
+        self.assertEquals(len(packages), 2)
+        self.assertEquals(packages[0].name, 'package1')
+        self.assertEquals(packages[1].name, 'package2')
+
+        # WNPP/sponsorship-requests
+        packages = Bug.objects._guess_packages(
+            'wnpp',
+            'ITP: foo -- A stable and useful software'
+        )
+
+        self.assertEquals(len(packages), 1)
+        self.assertEquals(packages[0].name, 'foo')
+
+        # WNPP/sponsorship-requests, wrong subject
+        packages = Bug.objects._guess_packages(
+            'wnpp',
+            'wait, there is a format for the subject?'
+        )
+
+        self.assertEquals(len(packages), 0)