add touch method to model

[koenpunt]

Work to implement suggested feature: #486

[daniel-aranda]

Thanks for adding this. Please add tests. My two cents with a skeleton of tests for the change:

    public function test_touch(){

        $author = new Author();
        $author->save();
        $updated_at = $author->updated_at;
        sleep(1);

        $author->touch();

        $this->assert_not_null($author->updated_at);
        $this->assert_not_equals($updated_at, $author->updated_at);
        $this->assert_greater_than($updated_at, $author->updated_at);

    }

[koenpunt]

It's not for nothing I labeled this PR "work in progress" ;)

[koenpunt]

And I'm not a fan of using sleep in tests.

It's probably faster to set the date explicitly (untested):

$author = new Author();
$updated_at = $author->updated_at = new DateTime('yesterday');
// NB. not sure if updated_at is also updated when it has been modified manually.
$author->save();

$author->touch();

$this->assertGreaterThan($updated_at, $author->updated_at);

But like I said, there still is some work to do.

[daniel-aranda]

Cool, just wanted to collaborate. I'm also not a fan of using Sleep, I agree with that. Just wanted to piggy back to existing tests. But definitely my vote is also to the Datetime set. Thanks.