diff --git a/Event/EventManager.php b/Event/EventManager.php
index d2aab8c11..8f86b7181 100644
--- a/Event/EventManager.php
+++ b/Event/EventManager.php
@@ -162,7 +162,7 @@ final class EventManager
      */
     public function detach(string $group) : bool
     {
-        return $this->detachCallback($group) || $this->detachGroup($group);
+        return $this->detachCallback($group) | $this->detachGroup($group);
     }
 
     /**
diff --git a/tests/Event/EventManagerTest.php b/tests/Event/EventManagerTest.php
index 8fc996704..70c5dfd3d 100644
--- a/tests/Event/EventManagerTest.php
+++ b/tests/Event/EventManagerTest.php
@@ -32,6 +32,7 @@ class EventManagerTest extends \PHPUnit\Framework\TestCase
         $event = new EventManager();
 
         self::assertEquals(0, $event->count());
+        self::assertFalse($event->trigger('invalid'));
     }
 
     public function testBase()
@@ -41,15 +42,12 @@ class EventManagerTest extends \PHPUnit\Framework\TestCase
         self::assertTrue($event->attach('group', function() { return true; }, false, false));
         self::assertFalse($event->attach('group', function() { return true; }, false, false));
         self::assertEquals(1, $event->count());
-
-        self::assertTrue($event->detach('group'));
-        self::assertFalse($event->trigger('group'));
-        self::assertEquals(0, $event->count());
     }
 
     public function testReset()
     {
         $event = new EventManager();
+
         self::assertTrue($event->attach('group', function() { return true; }, false, true));
         $event->addGroup('group', 'id1');
         $event->addGroup('group', 'id2');
@@ -58,17 +56,17 @@ class EventManagerTest extends \PHPUnit\Framework\TestCase
         self::assertTrue($event->trigger('group', 'id2'));
         self::assertFalse($event->trigger('group', 'id2'));
         self::assertEquals(1, $event->count());
-
-        self::assertTrue($event->detach('group'));
     }
 
     public function testDetach()
     {
         $event = new EventManager();
+
         self::assertTrue($event->attach('group', function() { return true; }, false, true));
         $event->addGroup('group', 'id1');
         $event->addGroup('group', 'id2');
 
+        self::assertEquals(1, $event->count());
         self::assertTrue($event->detach('group'));
         self::assertEquals(0, $event->count());
         self::assertFalse($event->trigger('group'));
@@ -77,6 +75,7 @@ class EventManagerTest extends \PHPUnit\Framework\TestCase
     public function testRemove()
     {
         $event = new EventManager();
+        
         self::assertTrue($event->attach('group1', function() { return true; }, true, false));
         self::assertTrue($event->attach('group2', function() { return true; }, true, false));
         self::assertEquals(2, $event->count());