public function testGetCallStack()
 {
     try {
         $this->instanceFunction();
         $this->fail();
     } catch (Exception $e) {
         $formatter = new ExceptionFormatter($e);
     }
     $calls = $formatter->getCallStack();
     $this->assertTrue(StringUtil::startsWith($calls[0], 'function genericFuncion()'));
     $this->assertTrue(StringUtil::startsWith($calls[1], 'ExceptionFormatterTest::{closure}()'));
     $this->assertTrue(StringUtil::startsWith($calls[2], 'ExceptionFormatterTest::staticFunction()'));
     $this->assertTrue(StringUtil::startsWith($calls[3], 'ExceptionFormatterTest->instanceFunction()'));
 }