Airbrake\Configuration::addFilter PHP Method

    public function addFilter($keyName)
    {
        if (!$keyName instanceof Filter\FilterInterface) {
            $keyName = new Filter($keyName);
        }
        $this->parameterFilters[] = $keyName;
        return $this;
    }

 public function testCustomFilter()
 {
     $initial = array('foo' => 1, 'bar' => 2);
     $expected = array('bar' => 2);
     $instance = new CustomFilter('foo');
     $config = new Configuration('test', array('postData' => $initial));
     $config->addFilter($instance);
     $this->assertEquals($expected, $config->getParameters());
 }