=== modified file 'modules/simpletest/simpletest.api.php'
--- modules/simpletest/simpletest.api.php	2009-07-11 13:56:21 +0000
+++ modules/simpletest/simpletest.api.php	2009-12-19 10:13:01 +0000
@@ -12,6 +12,21 @@
  */
 
 /**
+ * Alter the list of tests.
+ *
+ * @param $groups
+ *   A two dimension array, the first key is the test group (as defined in
+ *   getInfo) the second is the name of the class and the value is the return
+ *   value of the getInfo method.
+ */
+function hook_simpletest_alter(&$groups) {
+  // An alternative session handler module would not want to run the original
+  // Session https handling test because it checks the sessions table in the
+  // database.
+  unset($groups['Session']['testHttpsSession']);
+}
+
+/**
  * A test group has started.
  *
  * This hook is called just once at the beginning of a test group.

=== modified file 'modules/simpletest/simpletest.module'
--- modules/simpletest/simpletest.module	2009-12-15 05:25:47 +0000
+++ modules/simpletest/simpletest.module	2009-12-19 09:59:35 +0000
@@ -368,6 +368,8 @@ function simpletest_test_get_all() {
         uksort($tests, 'strnatcasecmp');
       }
 
+      // Allow modules extending core tests to disable originals.
+      drupal_alter('simpletest', $groups);
       cache_set('simpletest', $groups);
     }
   }