diff --git a/lib/phpunit/classes/advanced_testcase.php b/lib/phpunit/classes/advanced_testcase.php
index 7ee75ebf374..1c0bd816cd9 100644
--- a/lib/phpunit/classes/advanced_testcase.php
+++ b/lib/phpunit/classes/advanced_testcase.php
@@ -307,6 +307,44 @@ abstract class advanced_testcase extends base_testcase {
         $this->resetDebugging();
     }
 
+    /**
+     * Asserts how many times debugging has been called.
+     *
+     * @param int $expectedcount The expected number of times
+     * @param array $debugmessages Expected debugging messages, one for each expected message.
+     * @param array $debuglevels Expected debugging levels, one for each expected message.
+     * @param string $message
+     * @return void
+     */
+    public function assertDebuggingCalledCount($expectedcount, $debugmessages = array(), $debuglevels = array(), $message = '') {
+        if (!is_int($expectedcount)) {
+            throw new coding_exception('assertDebuggingCalledCount $expectedcount argument should be an integer.');
+        }
+
+        $debugging = $this->getDebuggingMessages();
+        $this->assertEquals($expectedcount, count($debugging), $message);
+
+        if ($debugmessages) {
+            if (!is_array($debugmessages) || count($debugmessages) != $expectedcount) {
+                throw new coding_exception('assertDebuggingCalledCount $debugmessages should contain ' . $expectedcount . ' messages');
+            }
+            foreach ($debugmessages as $key => $debugmessage) {
+                $this->assertSame($debugmessage, $debugging[$key]->message, $message);
+            }
+        }
+
+        if ($debuglevels) {
+            if (!is_array($debuglevels) || count($debuglevels) != $expectedcount) {
+                throw new coding_exception('assertDebuggingCalledCount $debuglevels should contain ' . $expectedcount . ' messages');
+            }
+            foreach ($debuglevels as $key => $debuglevel) {
+                $this->assertSame($debuglevel, $debugging[$key]->level, $message);
+            }
+        }
+
+        $this->resetDebugging();
+    }
+
     /**
      * Call when no debugging() messages expected.
      * @param string $message
diff --git a/lib/tests/event_test.php b/lib/tests/event_test.php
index 55cdbf9acd5..f260cc61818 100644
--- a/lib/tests/event_test.php
+++ b/lib/tests/event_test.php
@@ -29,6 +29,8 @@ require_once(__DIR__.'/fixtures/event_fixtures.php');
 
 class core_event_testcase extends advanced_testcase {
 
+    const DEBUGGING_MSG = 'Events API using $handlers array has been deprecated in favour of Events 2 API, please use it instead.';
+
     public function test_event_properties() {
         global $USER;
 
@@ -591,6 +593,7 @@ class core_event_testcase extends advanced_testcase {
 
         $DB->delete_records('log', array());
         events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
         $DB->delete_records_select('events_handlers', "component <> 'unittest'");
         events_get_handlers('reset');
         $this->assertEquals(3, $DB->count_records('events_handlers'));
@@ -601,10 +604,12 @@ class core_event_testcase extends advanced_testcase {
 
         $event1 = \core_tests\event\unittest_executed::create(array('context'=>\context_system::instance(), 'other'=>array('sample'=>5, 'xx'=>10)));
         $event1->trigger();
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
 
         $event2 = \core_tests\event\unittest_executed::create(array('context'=>\context_system::instance(), 'other'=>array('sample'=>6, 'xx'=>11)));
         $event2->nest = true;
         $event2->trigger();
+        $this->assertDebuggingCalledCount(2, array(self::DEBUGGING_MSG, self::DEBUGGING_MSG), array(DEBUG_DEVELOPER, DEBUG_DEVELOPER));
 
         $this->assertSame(
             array('observe_all-5', 'observe_one-5', 'legacy_handler-0', 'observe_all-nesting-6', 'legacy_handler-0', 'observe_one-6', 'observe_all-666', 'observe_one-666', 'legacy_handler-0'),
diff --git a/lib/tests/eventslib_test.php b/lib/tests/eventslib_test.php
index 0428744a24f..c62d5cf2e4f 100644
--- a/lib/tests/eventslib_test.php
+++ b/lib/tests/eventslib_test.php
@@ -29,6 +29,8 @@ defined('MOODLE_INTERNAL') || die();
 
 class core_eventslib_testcase extends advanced_testcase {
 
+    const DEBUGGING_MSG = 'Events API using $handlers array has been deprecated in favour of Events 2 API, please use it instead.';
+
     /**
      * Create temporary entries in the database for these tests.
      * These tests have to work no matter the data currently in the database
@@ -40,7 +42,6 @@ class core_eventslib_testcase extends advanced_testcase {
         // Set global category settings to -1 (not force).
         eventslib_sample_function_handler('reset');
         eventslib_sample_handler_class::static_method('reset');
-        events_update_definition('unittest');
 
         $this->resetAfterTest();
     }
@@ -51,6 +52,9 @@ class core_eventslib_testcase extends advanced_testcase {
     public function test_events_update_definition__install() {
         global $DB;
 
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $dbcount = $DB->count_records('events_handlers', array('component'=>'unittest'));
         $handlers = array();
         require(__DIR__.'/fixtures/events.php');
@@ -63,6 +67,9 @@ class core_eventslib_testcase extends advanced_testcase {
     public function test_events_update_definition__uninstall() {
         global $DB;
 
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         events_uninstall('unittest');
         $this->assertEquals(0, $DB->count_records('events_handlers', array('component'=>'unittest')), 'All handlers should be uninstalled: %s');
     }
@@ -72,6 +79,10 @@ class core_eventslib_testcase extends advanced_testcase {
      */
     public function test_events_update_definition__update() {
         global $DB;
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         // First modify directly existing handler.
         $handler = $DB->get_record('events_handlers', array('component'=>'unittest', 'eventname'=>'test_instant'));
 
@@ -82,6 +93,7 @@ class core_eventslib_testcase extends advanced_testcase {
 
         // Update the definition, it should revert the handler back.
         events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
         $handler = $DB->get_record('events_handlers', array('component'=>'unittest', 'eventname'=>'test_instant'));
         $this->assertSame($handler->handlerfunction, $original, 'update should sync db with file definition: %s');
     }
@@ -90,15 +102,27 @@ class core_eventslib_testcase extends advanced_testcase {
      * Tests events_trigger_is_registered() function.
      */
     public function test_events_is_registered() {
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $this->assertTrue(events_is_registered('test_instant', 'unittest'));
+        $this->assertDebuggingCalled('events_is_registered() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
     }
 
     /**
      * Tests events_trigger_legacy() function.
      */
     public function test_events_trigger_legacy_instant() {
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $this->assertEquals(0, events_trigger_legacy('test_instant', 'ok'));
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
         $this->assertEquals(0, events_trigger_legacy('test_instant', 'ok'));
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
         $this->assertEquals(2, eventslib_sample_function_handler('status'));
     }
 
@@ -106,9 +130,16 @@ class core_eventslib_testcase extends advanced_testcase {
      * Tests events_trigger_legacy() function.
      */
     public function test_events_trigger__cron() {
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $this->assertEquals(0, events_trigger_legacy('test_cron', 'ok'));
         $this->assertEquals(0, eventslib_sample_handler_class::static_method('status'));
         events_cron('test_cron');
+        // The events_cron one + one for each triggered event above (triggered in events_dispatch).
+        $this->assertDebuggingCalledCount(2, array(self::DEBUGGING_MSG, self::DEBUGGING_MSG),
+            array(DEBUG_DEVELOPER, DEBUG_DEVELOPER));
         $this->assertEquals(1, eventslib_sample_handler_class::static_method('status'));
     }
 
@@ -116,10 +147,20 @@ class core_eventslib_testcase extends advanced_testcase {
      * Tests events_pending_count() function.
      */
     public function test_events_pending_count() {
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         events_trigger_legacy('test_cron', 'ok');
+        $this->assertDebuggingNotCalled();
         events_trigger_legacy('test_cron', 'ok');
+        $this->assertDebuggingNotCalled();
         events_cron('test_cron');
+        // The events_cron one + one for each triggered event above (triggered in events_dispatch).
+        $this->assertDebuggingCalledCount(3);
         $this->assertEquals(0, events_pending_count('test_cron'), 'all messages should be already dequeued: %s');
+        $this->assertDebuggingCalled('events_pending_count() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
     }
 
     /**
@@ -127,34 +168,64 @@ class core_eventslib_testcase extends advanced_testcase {
      */
     public function test_events_trigger__failed_instant() {
         global $CFG;
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $olddebug = $CFG->debug;
 
         $this->assertEquals(1, events_trigger_legacy('test_instant', 'fail'), 'fail first event: %s');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
         $this->assertEquals(1, events_trigger_legacy('test_instant', 'ok'), 'this one should fail too: %s');
+        $this->assertDebuggingNotCalled();
 
         $this->assertEquals(0, events_cron('test_instant'), 'all events should stay in queue: %s');
-        $this->assertDebuggingCalled();
+        // events_cron + one for each dispatched event.
+        $this->assertDebuggingCalledCount(3);
 
         $this->assertEquals(2, events_pending_count('test_instant'), 'two events should in queue: %s');
+        $this->assertDebuggingCalled('events_pending_count() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
+
         $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.
         $this->assertEquals(1, events_trigger_legacy('test_instant', 'ok'), 'this one should go to queue directly: %s');
+        $this->assertDebuggingNotCalled();
+
         $this->assertEquals(3, events_pending_count('test_instant'), 'three events should in queue: %s');
+        $this->assertDebuggingCalled('events_pending_count() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
+
         $this->assertEquals(0, eventslib_sample_function_handler('status'), 'verify previous event was not dispatched: %s');
         $this->assertEquals(3, events_cron('test_instant'), 'all events should be dispatched: %s');
+        // events_cron + one for each dispatched event.
+        $this->assertDebuggingCalledCount(4);
+
         $this->assertEquals(3, eventslib_sample_function_handler('status'), 'verify three events were dispatched: %s');
         $this->assertEquals(0, events_pending_count('test_instant'), 'no events should in queue: %s');
+        $this->assertDebuggingCalled('events_pending_count() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
+
         $this->assertEquals(0, events_trigger_legacy('test_instant', 'ok'), 'this event should be dispatched immediately: %s');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $this->assertEquals(4, eventslib_sample_function_handler('status'), 'verify event was dispatched: %s');
         $this->assertEquals(0, events_pending_count('test_instant'), 'no events should in queue: %s');
+        $this->assertDebuggingCalled('events_pending_count() has been deprecated along with all Events 1 API in favour of Events 2' .
+            ' API, please use it instead.', DEBUG_DEVELOPER);
     }
 
     /**
      * Tests events_trigger() function.
      */
     public function test_events_trigger_debugging() {
+
+        events_update_definition('unittest');
+        $this->assertDebuggingCalled(self::DEBUGGING_MSG, DEBUG_DEVELOPER);
+
         $this->assertEquals(0, events_trigger('test_instant', 'ok'));
-        $this->assertDebuggingCalled();
+        $debugmessages = array('events_trigger() is deprecated, please use new events instead', self::DEBUGGING_MSG);
+        $this->assertDebuggingCalledCount(2, $debugmessages, array(DEBUG_DEVELOPER, DEBUG_DEVELOPER));
     }
 }