tests: check basic properties of objectstore

Check the very basic operations of the object store, i.e. creating
multiple trees with different object_ids works and results in the
correct number of objects and references.

test/test_objectstore.py

@@ -20,6 +20,33 @@ class TestObjectStore(unittest.TestCase):
         if not os.getenv("OSBUILD_TEST_STORE"):
             shutil.rmtree(cls.store)
 
+    def test_basic(self):
+        # always use a temporary store so item counting works
+        with tempfile.TemporaryDirectory(dir="/var/tmp") as tmp:
+            object_store = objectstore.ObjectStore(tmp)
+            with object_store.new("a") as tree:
+                p = Path(f"{tree}/A")
+                p.touch()
+
+            assert os.path.exists(f"{object_store.refs}/a")
+            assert os.path.exists(f"{object_store.refs}/a/A")
+            assert len(os.listdir(object_store.refs)) == 1
+            assert len(os.listdir(object_store.objects)) == 1
+            assert len(os.listdir(f"{object_store.refs}/a/")) == 1
+
+            with object_store.new("b") as tree:
+                p = Path(f"{tree}/A")
+                p.touch()
+                p = Path(f"{tree}/B")
+                p.touch()
+
+            assert os.path.exists(f"{object_store.refs}/b")
+            assert os.path.exists(f"{object_store.refs}/b/B")
+
+            assert len(os.listdir(object_store.refs)) == 2
+            assert len(os.listdir(object_store.objects)) == 2
+            assert len(os.listdir(f"{object_store.refs}/b/")) == 2
+
     def test_snapshot(self):
         object_store = objectstore.ObjectStore(self.store)
         with object_store.new("b") as tree: