Update test to work across any WordPress version

This is going to have different results across different versions of
WordPress now, because output depends on the upstream requirements of
what we are testing. Update test so that the update status is variable
and we specify the fields otherwise it would sometimes show additional
fields explaining the reason an update is unavailable

Author: mrsdizzie

features/upgradables.feature

@@ -55,10 +55,14 @@ Feature: Manage WordPress themes and plugins
     Then STDOUT should not be empty
     And save STDOUT as {UPDATE_VERSION}
 
-    When I run `wp <type> list`
+    When I run `wp <type> list --name=<item> --field=update`
+    Then STDOUT should not be empty
+    And save STDOUT as {UPDATE}
+
+    When I run `wp <type> list --fields=name,status,update,version,update_version,auto_update`
     Then STDOUT should be a table containing rows:
-      | name   | status   | update    | version   | update_version   | auto_update |
-      | <item> | inactive | available | <version> | {UPDATE_VERSION} | off         |
+      | name   | status   | update    | version    | update_version   | auto_update |
+      | <item> | inactive | {UPDATE}  | <version>  | {UPDATE_VERSION} | off         |
 
     When I run `wp <type> list --field=name`
     Then STDOUT should contain: