Cleaning up some coverage and a few bits.

test_specs/mixedref-burgershop.openapi.yaml

@@ -229,6 +229,12 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/Error'
+        "400":
+          description: Unexpected error. Sorry.
+          content:
+            application/json:
+              schema:
+                $ref: 'https://raw.githubusercontent.com/daveshanley/vacuum/main/model/test_files/burgershop.openapi.yaml'
 components:
   schemas:
     Error:

test_specs/single-definition.yaml

@@ -0,0 +1,9 @@
+components:
+  schemas:
+    Thing:
+      type: object
+      description: A thing that does nothing.
+      properties:
+        message:
+          type: string
+          description: I am pointless.