Move node fetching to a prologue.

Signed-off-by: dblock <[email protected]>

tests/default/security/api/certificates.yaml

@@ -4,20 +4,18 @@ description: Test certificates endpoints.
 version: '> 2.14'
 
 # ADMIN-CERT only. These tests require explicit rest api admin privileges.
-chapters:
-  - synopsis: Get node.
-    id: get_node
-    path: /_cat/nodes
+prologues:
+  - path: /_cat/nodes
+    id: node
     method: GET
     parameters:
-      h:
-        - id
       full_id: true
-    response:
-      status: 200
-      content_type: text/plain
+      size: 1
+      format: json
+      h: id
     output:
-      node_id: payload
+      id: payload[0].id
+chapters:
   - synopsis: Get all certificates.
     path: /_plugins/_security/api/certificates
     method: GET
@@ -29,7 +27,7 @@ chapters:
     path: /_plugins/_security/api/certificates/{node_id}
     method: GET
     parameters:
-      node_id: ${get_node.node_id}
+      node_id: ${node.id}
       cert_type: all
     response:
-      status: 403
+      status: 403