passlib.exc: has_backend() now raises explicit UnknownBackendError, not ValueError

1 files changed, 13 insertions, 0 deletions

diff --git a/passlib/exc.py b/passlib/exc.py
index d044aec..ffb9fe6 100644
--- a/passlib/exc.py
+++ b/passlib/exc.py
@@ -2,6 +2,19 @@
 #=============================================================================
 # exceptions
 #=============================================================================
+class UnknownBackendError(ValueError):
+    """
+    Error raised if multi-backend handler doesn't recognize backend name.
+    Inherits from :exc:`ValueError`.
+
+    .. versionadded:: 1.7
+    """
+    def __init__(self, hasher, backend):
+        self.hasher = hasher
+        self.backend = backend
+        message = "%s: unknown backend: %r" % (hasher.name, backend)
+        ValueError.__init__(self, message)
+
 class MissingBackendError(RuntimeError):
     """Error raised if multi-backend handler has no available backends;
     or if specifically requested backend is not available.