MDL-41900 events: avoid new debug call within unit tests

lib/tests/eventslib_test.php

@@ -126,9 +126,18 @@ public function test_events_pending_count() {
      * Tests events_trigger() function when instant handler fails.
      */
     public function test_events_trigger__failed_instant() {
+        global $CFG;
+        $olddebug = $CFG->debug;
+
         $this->assertEquals(1, events_trigger('test_instant', 'fail'), 'fail first event: %s');
         $this->assertEquals(1, events_trigger('test_instant', 'ok'), 'this one should fail too: %s');
+
+        // We disable debugging for this next test. It'll make some noise when it fails to dispatch
+        // so that problems don't go permanently unnoticed.
+        $CFG->debug = 0;
         $this->assertEquals(0, events_cron('test_instant'), 'all events should stay in queue: %s');
+        $CFG->debug = $olddebug;
+
         $this->assertEquals(2, events_pending_count('test_instant'), 'two events should in queue: %s');
         $this->assertEquals(0, eventslib_sample_function_handler('status'), 'verify no event dispatched yet: %s');
         eventslib_sample_function_handler('ignorefail'); // Ignore "fail" eventdata from now on.