overall better handling and usage of exceptions

libs/tools.py

@@ -1,6 +1,6 @@
 from ipaddress import ip_address, ip_network, IPv4Address, IPv4Network
 
-from bundlewrap.exceptions import NoSuchGroup, NoSuchNode
+from bundlewrap.exceptions import NoSuchGroup, NoSuchNode, BundleError
 from bundlewrap.utils.text import bold, red
 from bundlewrap.utils.ui import io
 
@@ -78,3 +78,11 @@ def remove_more_specific_subnets(input_subnets) -> list:
         out.append(str(net))
 
     return out
+
+
+def require_bundle(node, bundle, hint=''):
+    # It's considered bad style to use assert statements outside of tests.
+    # That's why this little helper function exists, so we have an easy
+    # way of defining bundle requirements in other bundles.
+    if not node.has_bundle(bundle):
+        raise BundleError(f'{node.name} requires bundle {bundle}, but wasn\'t found! {hint}')