Neos\Flow\Mvc\Controller\Arguments::addArgument PHP Method

    public function addArgument(Argument $argument)
    {
        $this->offsetSet(null, $argument);
    }

 /**
  * @test
  */
 public function getValidationResultsShouldFetchAllValidationResltsFromArguments()
 {
     $error1 = new FlowError\Error('Validation error', 1234);
     $error2 = new FlowError\Error('Validation error 2', 1235);
     $results1 = new FlowError\Result();
     $results1->addError($error1);
     $results2 = new FlowError\Result();
     $results2->addError($error2);
     $argument1 = $this->getMockBuilder(Argument::class)->setMethods(['getValidationResults'])->setConstructorArgs(['name1', 'string'])->getMock();
     $argument1->expects($this->once())->method('getValidationResults')->will($this->returnValue($results1));
     $argument2 = $this->getMockBuilder(Argument::class)->setMethods(['getValidationResults'])->setConstructorArgs(['name2', 'string'])->getMock();
     $argument2->expects($this->once())->method('getValidationResults')->will($this->returnValue($results2));
     $arguments = new Arguments();
     $arguments->addArgument($argument1);
     $arguments->addArgument($argument2);
     $this->assertSame(['name1' => [$error1], 'name2' => [$error2]], $arguments->getValidationResults()->getFlattenedErrors());
 }