Bart\Configuration\TestConfig::speed PHP Method

    public function speed()
    {
        return $this->getValue('travel', 'speed', null, false);
    }

 public function testNotRequiredConfigsWhenMissingWithNullDefault()
 {
     $configs = new TestConfig();
     $configs->configureForTesting(self::$sampleConfigs);
     $this->assertNull($configs->speed(), 'Speed configuration');
 }