raise InvalidSpec if no colon

edbob/exceptions.py

@@ -73,6 +73,12 @@ class LoadSpecError(Exception):
         return None
 
 
+class InvalidSpec(LoadSpecError):
+
+    def specifics(self):
+        return "invalid spec"
+
+
 class ModuleMissingAttribute(LoadSpecError):
     """
     Raised during :func:`edbob.load_spec()` when the module imported okay but

edbob/modules.py

@@ -82,6 +82,9 @@ def load_spec(spec):
     necessary.
     """
 
+    if spec.count(':') != 1:
+        raise exceptions.InvalidSpec(spec)
+
     module_path, obj = spec.split(':')
     module = import_module_path(module_path)
     try: