test: '{. -> ./mod}/test_util_osrelease.py'

Move the os-release tests to the module-level tests and align its
coding-style with the others.

.github/workflows/tests.yml

@@ -77,11 +77,6 @@ jobs:
           cd osbuild
           python3 -m unittest -v test.test_objectstore
 
-      - name: Run test_osrelease
-        run: |
-          cd osbuild
-          python3 -m unittest -v test.test_osrelease
-
   rpm_build:
     name: "📦 RPM"
     runs-on: ubuntu-latest

test/mod/test_util_osrelease.py

@@ -1,9 +1,14 @@
+#
+# Tests for the `osbuild.util.osrelease` module.
+#
+
 import os
 import unittest
 
 from osbuild.util import osrelease
 
-class TestOSRelease(unittest.TestCase):
+
+class TestUtilOSRelease(unittest.TestCase):
     def test_non_existant(self):
         """Verify default os-release value, if no files are given."""
         self.assertEqual(osrelease.describe_os(), "linux")