emit before/after data

Author: isoos

app/lib/admin/actions/package_publisher_set.dart

@@ -56,6 +56,9 @@ final packagePublisherSet = AdminAction(
     }
 
     final pkg = await packageBackend.lookupPackage(packageName);
-    return {'publisherId': pkg!.publisherId};
+    return {
+      'before': {'publisherId': currentPublisherId},
+      'after': {'publisherId': pkg!.publisherId},
+    };
   },
 );

app/test/admin/package_actions_test.dart

@@ -86,7 +86,10 @@ void main() {
             arguments: {'package': 'oxygen', 'publisher': 'example.com'},
           ),
         );
-        expect(rs.output, {'publisherId': 'example.com'});
+        expect(rs.output, {
+          'before': {'publisherId': null},
+          'after': {'publisherId': 'example.com'},
+        });
       },
     );
   });