test: add expects() and remove assertTrue(true)

Author: kenjis

tests/system/Email/EmailTest.php

@@ -143,16 +143,14 @@ public function testDestructDoesNotThrowException()
             ->disableOriginalConstructor()
             ->onlyMethods(['sendCommand'])
             ->getMock();
-        $email->method('sendCommand')
+        $email->expects($this->once())->method('sendCommand')
             ->willThrowException(new ErrorException('SMTP Error.'));
 
         // Force resource to be injected into the property
         $SMTPConnect = fopen(__FILE__, 'rb');
         $this->setPrivateProperty($email, 'SMTPConnect', $SMTPConnect);
 
         $email->__destruct();
-
-        $this->assertTrue(true);
     }
 
     private function createMockEmail(): MockEmail