util,test: add test for new shlex based os-release parsing

This commit adds a tiny unit test for the new `shlex` based
os-release parsing and tweaks the error message in a small
and non-functional way (just because it's slightly nicer
for a user). The test checks for three keys NAME which is
quoted with `"`, ID which is not quoted and OSTREE_VERSION
which is quoted with `'`.

osbuild/util/osrelease.py

@@ -35,8 +35,10 @@ def parse_files(*paths):
                     continue
                 key, value = line.split("=", 1)
                 split_value = shlex.split(value)
-                if not split_value or len(split_value) > 1:
-                    raise ValueError(f"Key '{key}' has an empty value or more than one token: {value}")
+                if not split_value:
+                    raise ValueError(f"Key '{key}' has an empty value")
+                if len(split_value) > 1:
+                    raise ValueError(f"Key '{key}' has more than one token: {value}")
                 osrelease[key] = split_value[0]
 
     return osrelease

test/mod/test_util_osrelease.py

@@ -5,6 +5,8 @@
 import os
 import unittest
 
+import pytest
+
 from osbuild.util import osrelease
 
 from .. import test
@@ -28,3 +30,23 @@ class TestUtilOSRelease(test.TestBase):
         for entry in os.scandir(os.path.join(self.locate_test_data(), "os-release")):
             with self.subTest(entry.name):
                 self.assertEqual(osrelease.describe_os(entry.path), entry.name)
+
+
+def test_osreleae_f40_really_coreos_happy():
+    here = os.path.dirname(__file__)
+    res = osrelease.parse_files(os.path.join(here, "../data/os-release/fedora40"))
+    assert res["NAME"] == 'Fedora Linux'
+    assert res["ID"] == 'fedora'
+    assert res["OSTREE_VERSION"] == '40.20241106.dev.0'
+
+
+@pytest.mark.parametrize("content,expected_err", [
+    ("OSTREE=", "Key 'OSTREE' has an empty value"),
+    ("OSTREE='foo' 'bar'", "Key 'OSTREE' has more than one token: 'foo' 'bar'"),
+])
+def test_osrelease_bad_split_empty(tmp_path, content, expected_err):
+    bad_os_release_path = tmp_path / "os-release"
+    bad_os_release_path.write_text(content + "\n")
+    with pytest.raises(ValueError) as exc:
+        osrelease.parse_files(bad_os_release_path)
+    assert str(exc.value) == expected_err