public function testRegisterErrorHandler() { $writer = new MockWriter(); $this->logger->addWriter($writer); $this->assertTrue(Logger::registerErrorHandler($this->logger)); // check for single error handler instance $this->assertFalse(Logger::registerErrorHandler($this->logger)); // generate a warning echo $test; Logger::unregisterErrorHandler(); $this->assertEquals($writer->events[0]['message'], 'Undefined variable: test'); }