Extract shared adapter validation helpers

dns_sync/adapter_support.py

@@ -0,0 +1,41 @@
+from .adapters import Endpoint, NormalizedObject, PlanAction
+
+
+def require_endpoint_plugin(
+    endpoint: Endpoint,
+    plugin_name: str,
+) -> None:
+    expected = plugin_name.strip().lower()
+
+    if not expected:
+        raise ValueError("Adapter plugin name cannot be empty")
+
+    if endpoint.plugin != expected:
+        raise RuntimeError(
+            f"Adapter {expected!r} cannot use endpoint "
+            f"{endpoint.identity!r}"
+        )
+
+
+def require_action_endpoint(
+    action: PlanAction,
+    endpoint: Endpoint,
+) -> None:
+    if action.endpoint_id != endpoint.identity:
+        raise RuntimeError(
+            f"Plan action for {action.endpoint_id!r} does not belong "
+            f"to adapter endpoint {endpoint.identity!r}"
+        )
+
+
+def require_desired(
+    action: PlanAction,
+    *,
+    context: str = "Adapter apply",
+) -> NormalizedObject:
+    if action.desired is None:
+        raise RuntimeError(
+            f"{context} requires desired state"
+        )
+
+    return action.desired

dns_sync/plugins/adapters/npm.py

@@ -13,6 +13,11 @@ from ...adapters import (
     PlanOperation,
     RetireRequest,
 )
+from ...adapter_support import (
+    require_action_endpoint,
+    require_desired,
+    require_endpoint_plugin,
+)
 from ...certificates.material import CertificateMaterial
 from ...npm_client import NpmClient
 from ...object_normalizer import normalize_discovered_object
@@ -67,6 +72,7 @@ class Plugin:
     )
 
     def __init__(self, config, endpoint):
+        require_endpoint_plugin(endpoint, self.name)
         self.config = config
         self.endpoint = endpoint
         self.client = NpmClient(config, endpoint)
@@ -593,17 +599,15 @@ class Plugin:
         self,
         action: PlanAction,
     ) -> ApplyResult | None:
-        desired = action.desired
+        desired = require_desired(
+            action,
+            context="NPM apply",
+        )
 
-        if desired is None:
-            raise RuntimeError(
-                "NPM apply requires desired state"
-            )
-
-        if action.endpoint_id != self.endpoint.identity:
-            raise RuntimeError(
-                "NPM apply action endpoint does not match adapter"
-            )
+        require_action_endpoint(
+            action,
+            self.endpoint,
+        )
 
         if (
             desired.object_type == CERTIFICATES