Allow supplying keypair when creating mutable dirs

src/allmydata/client.py

@@ -1125,8 +1125,18 @@ class _Client(node.Node, pollmixin.PollMixin):
         # may get an opaque node if there were any problems.
         return self.nodemaker.create_from_cap(write_uri, read_uri, deep_immutable=deep_immutable, name=name)
 
-    def create_dirnode(self, initial_children=None, version=None):
-        d = self.nodemaker.create_new_mutable_directory(initial_children, version=version)
+    def create_dirnode(
+        self,
+        initial_children=None,
+        version=None,
+        *,
+        unique_keypair: tuple[rsa.PublicKey, rsa.PrivateKey] | None = None
+    ):
+        d = self.nodemaker.create_new_mutable_directory(
+            initial_children,
+            version=version,
+            keypair=unique_keypair,
+        )
         return d
 
     def create_immutable_dirnode(self, children, convergence=None):

src/allmydata/nodemaker.py

@@ -135,7 +135,13 @@ class NodeMaker(object):
         d.addCallback(lambda res: n)
         return d
 
-    def create_new_mutable_directory(self, initial_children=None, version=None):
+    def create_new_mutable_directory(
+        self,
+        initial_children=None,
+        version=None,
+        *,
+        keypair: tuple[PublicKey, PrivateKey] | None = None,
+    ):
         if initial_children is None:
             initial_children = {}
         for (name, (node, metadata)) in initial_children.items():
@@ -145,7 +151,8 @@ class NodeMaker(object):
         d = self.create_mutable_file(lambda n:
                                      MutableData(pack_children(initial_children,
                                                     n.get_writekey())),
-                                     version=version)
+                                     version=version,
+                                     keypair=keypair)
         d.addCallback(self._create_dirnode)
         return d