Integration testing for mirror info script

This adds a job to assert the mirror-info script is created correctly.

Change-Id: I56f7b1d6e94c81dceebb14d27ba4aa59e9874245

tests/base.yaml

@@ -1,3 +1,4 @@
 # Roles that are part of the 'base' job
 
 - include: configure-mirrors.yaml
+- include: mirror-info.yaml

tests/mirror-info.yaml

@@ -0,0 +1,14 @@
+- name: Test the creation of the mirror-info script
+  hosts: all
+  roles:
+    role: mirror-info
+    mirror_fqdn: "{{ zuul_site_mirror_fqdn }}"
+  post_tasks:
+    - name: Check mirror script
+      stat:
+        path: /etc/ci/mirror_info.sh
+      register: stat_result
+    - assert:
+        that:
+          - "stat_result.stat.exists"
+          - "stat_result.stat.mode == 0644"