test/assembler: check for ostree version metadata

Set the OS version of the commit via the new `os_version` option
and make sure that it is in the compose info as well as in the
commit metadata.

test/data/manifests/fedora-ostree-commit.json

@@ -682,7 +682,8 @@
     "assembler": {
       "name": "org.osbuild.ostree.commit",
       "options": {
-        "ref": "fedora/x86_64/osbuild"
+        "ref": "fedora/x86_64/osbuild",
+        "os_version": "32"
       }
     }
   },

test/data/manifests/mpp-fedora-ostree-commit.json

@@ -97,7 +97,8 @@
     "assembler": {
       "name": "org.osbuild.ostree.commit",
       "options": {
-        "ref": "fedora/x86_64/osbuild"
+        "ref": "fedora/x86_64/osbuild",
+        "os_version": "32"
       }
     }
   }

test/run/test_assemblers.py

@@ -127,9 +127,11 @@ class TestAssemblers(test.TestBase):
                 commit_id = compose["ostree-commit"]
                 ref = compose["ref"]
                 rpmostree_inputhash = compose["rpm-ostree-inputhash"]
+                os_version = compose["ostree-version"]
                 assert commit_id
                 assert ref
                 assert rpmostree_inputhash
+                assert os_version
 
                 md = subprocess.check_output(
                     [
@@ -141,6 +143,16 @@ class TestAssemblers(test.TestBase):
                     ], encoding="utf-8").strip()
                 self.assertEqual(md, f"'{rpmostree_inputhash}'")
 
+                md = subprocess.check_output(
+                    [
+                        "ostree",
+                        "show",
+                        "--repo", repo,
+                        "--print-metadata-key=version",
+                        commit_id
+                    ], encoding="utf-8").strip()
+                self.assertEqual(md, f"'{os_version}'")
+
     @unittest.skipUnless(test.TestBase.have_tree_diff(), "tree-diff missing")
     def test_qemu(self):
         loctl = loop.LoopControl()