/**
* @return Regularized
*/
private function makeGradient()
{
$mock = $this->getMockBuilder(Gradient::class)->setMethods(['cost', 'gradient'])->getMock();
$mock->method('cost')->willReturn(1.0);
$mock->method('gradient')->willReturn([16.0, 16.0]);
$gradient = new Regularized($mock);
return $gradient->ignoreFirstFeature(true)->setLambda(1.0)->setLevel(2);
}