public function testEmerg()
{
$l = new Logger(new File(__DIR__ . '/../tmp/app.log'));
$l->emerg('Test log message');
$this->assertTrue(file_exists(__DIR__ . '/../tmp/app.log'));
$this->assertGreaterThan(0, filesize(__DIR__ . '/../tmp/app.log'));
unlink(__DIR__ . '/../tmp/app.log');
}