store: raise BE specific exception, fixes #34

src/borgstore/backends/errors.py

@@ -7,6 +7,14 @@ class BackendError(Exception):
     """Base class for exceptions in this module."""
 
 
+class BackendURLInvalid(BackendError):
+    """Raised when trying to create a store using an invalid backend URL."""
+
+
+class NoBackendGiven(BackendError):
+    """Raised when trying to create a store and not giving a backend nor a URL."""
+
+
 class BackendAlreadyExists(BackendError):
     """Raised when a backend already exists."""
 

src/borgstore/store.py

@@ -17,7 +17,7 @@
 
 from .utils.nesting import nest
 from .backends._base import ItemInfo, BackendBase
-from .backends.errors import ObjectNotFound  # noqa
+from .backends.errors import ObjectNotFound, NoBackendGiven, BackendURLInvalid  # noqa
 from .backends.posixfs import get_file_backend
 from .backends.sftp import get_sftp_backend
 from .constants import DEL_SUFFIX
@@ -43,9 +43,9 @@ def __init__(self, url: Optional[str] = None, backend: Optional[BackendBase] = N
         if backend is None and url is not None:
             backend = get_backend(url)
             if backend is None:
-                raise ValueError(f"Invalid Backend Storage URL: {url}")
+                raise BackendURLInvalid(f"Invalid Backend Storage URL: {url}")
         if backend is None:
-            raise ValueError("You need to give a backend instance or a backend url.")
+            raise NoBackendGiven("You need to give a backend instance or a backend url.")
         self.backend = backend
         self._stats: Counter = Counter()
         # this is to emulate additional latency to what the backend actually offers: