Is bad idea to utilize helper functions on integration tests?

Question

In my job I have a small disagreement on whether we should utilize helper functions for making datasets especially in laravel framework. A sample for the test is:

namespace Tests\MyAppTests;
use PHPUnit\Framework\TestCase;
use Carbon\Carbon;
class MyTest extends TestCase
{
 private function makeATwoHourSpan(Carbon $now, &$start, &$end)
 {
 $start = new Carbon($now);
 $start->modify("-1 hour");
 $end = new Carbon($now);
 $end->modify("+1 hour");
 }
 public function testSomething()
 {
 $now=Carbon::now();
 $start=null;
 $end=null;
 this->makeATwoHourSpan($now, $start, $end);
 //Rest Of Test Here
 }
 public function testSomethingElse()
 {
 $now=Carbon::now();
 $start=null;
 $end=null;
 this->makeATwoHourSpan($now, $start, $end);
 //Rest Of Test Here
 }
}

The argument that my supervisor says is that using the makeATwoHourSpan method even though makes the code DRY it does not aid the readability of the test. Also he mentioned that a test should be autonomous and a easy to run as standalone without any helper function except the tools provided from the framework.

So my question is: Should I avoid utilizing "helper" functions especially when I make test data when I make tests, or having a function for data creation makes is the way to go?

• Robert Harvey: We're not here to solve your arguments with your supervisor for you. Software is software, including unit tests; precepts like DRY should apply everywhere. That said, your supervisor has a point; unit tests should be as "shallow" and as self-contained as possible. The only kind of helper methods I would entertain are those that have directly to do with the testing process, like Assert(). Business domain-specific helper methods like makeATwoHourSpan can be useful, but they don't really have a place in testing harnesses.
• Dherik: Why this makeATwoHourSpan method is "special"? I did not understand what you mean by "helper" function here. It's very common to create a base scenario before running a specific integration test. Otherwise, each integration test will have very long setups, with a lot of duplication among the tests and hard to maintain.
• Dimitrios Desyllas: This method helps me because I need to ganarate a specific datetime between a specirfic range hence the first way to do that is to create a daterange from a given time.

Answer 1

I think your supervisor is off track, and I think creating helper functions for integration tests is a perfect way to use OO and DRY principles in your test case design. I've made a career of developing integration tests and integration test frameworks, and do this same sort of thing and much more at every job I do. To not extract the duplicate code out of the tests into a shared function would make your tests harder (more expensive) to maintain. What good manager wants to decrease maintainability of source code, rather than increase it?

I might even go a step farther and move makeATwoHourSpan into a separate class, since odds are good that you will want other utility functions for creating and manipulating dates in your tests.