gravel/tests: fake up /var/lib/aquarium for KV store

Signed-off-by: Tim Serong <tserong@suse.com>

src/gravel/controllers/kv.py

@@ -57,7 +57,12 @@ def __init__(self):
         # Or, do we only open it when reading/writing in individual methods?
         # That would probably be better... (but would still have problems due to
         # simultaneous access, but we can always raise an exception in that case I guess?)
-        self._db = dbm.open(f"{var_lib_aquarium}/kvstore", "c")
+        try:
+            self._db = dbm.open(f"{var_lib_aquarium}/kvstore", "c")
+        except Exception as e:
+            # Only raise exceptions opening db file when *not* running unit tests
+            if "pytest" not in sys.modules:
+                raise e
         self._cluster: Optional[rados.Rados] = None
         self._connector_thread = threading.Thread(target=self._cluster_connect)
         self._run = True

src/gravel/tests/conftest.py

@@ -169,9 +169,13 @@ async def cancel_watch(self, watch_id: int) -> None:
 @pytest.fixture()
 @pytest.mark.asyncio
 async def aquarium_startup(
-    get_data_contents: Callable[[str, str], str], mocker: MockerFixture
+    get_data_contents: Callable[[str, str], str],
+    mocker: MockerFixture,
+    fs: fake_filesystem.FakeFilesystem,
 ):
+    # Need the following to fake up KV
     mock_ceph_modules(mocker)
+    fs.create_dir("/var/lib/aquarium")
 
     async def startup(aquarium_app: FastAPI, aquarium_api: FastAPI):
         from fastapi.logger import logger as fastapi_logger