feat: add launch_with_fn (#8694)

crates/node/builder/src/builder/states.rs

@@ -220,6 +220,14 @@ impl<T: FullNodeTypes, CB: NodeComponentsBuilder<T>> NodeBuilderWithComponents<T
         launcher.launch_node(self).await
     }
 
+    /// Launches the node with the given closure.
+    pub fn launch_with_fn<L, R>(self, launcher: L) -> R
+    where
+        L: FnOnce(Self) -> R,
+    {
+        launcher(self)
+    }
+
     /// Check that the builder can be launched
     ///
     /// This is useful when writing tests to ensure that the builder is configured correctly.

crates/node/builder/src/launch/mod.rs

@@ -58,6 +58,18 @@ pub trait LaunchNode<Target> {
     fn launch_node(self, target: Target) -> impl Future<Output = eyre::Result<Self::Node>> + Send;
 }
 
+impl<F, Target, Fut, Node> LaunchNode<Target> for F
+where
+    F: FnOnce(Target) -> Fut + Send,
+    Fut: Future<Output = eyre::Result<Node>> + Send,
+{
+    type Node = Node;
+
+    fn launch_node(self, target: Target) -> impl Future<Output = eyre::Result<Self::Node>> + Send {
+        self(target)
+    }
+}
+
 /// The default launcher for a node.
 #[derive(Debug)]
 pub struct DefaultNodeLauncher {