Integration Test with BrowserKitTesting

I get this error when performing my testing

There were 2 riskys:

1) Tests\Feature\DetailRusakPageTest::test_show_detail_rusak_page
Test code or tested code did not (only) close its own output buffers

2) Tests\Feature\RusakPageTest::test_show_rusak_page
Test code or tested code did not (only) close its own output buffers

and here are my test cases

public function test_show_detail_rusak_page()
    {
        $this->visit('/')
            ->type('[email protected]', 'email')
            ->type('admin', 'password')
            ->press('Sign in')
            ->seePageIs('/laporan')
            ->click('Titik Drainase Rusak')
            ->seePageIs('/rusak')
            ->click('1')
            ->seePageIs('/rusak/detail/ed8297b6-c25e-4c00-9f49-6dd10a1e60c6');
    }
public function test_show_rusak_page()
    {
        $this->visit('/')
            ->type('[email protected]', 'email')
            ->type('admin', 'password')
            ->press('Sign in')
            ->seePageIs('/laporan')
            ->click('Titik Drainase Rusak')
            ->seePageIs('/rusak');
    }

what does the error means? my other test cases work perfectly fine