Fix QueryParameterTest

Nice catch. And it's not just that the tests are never run, the tests are bugged when you do run them.

But instead of re-using $single, wouldn't it be easier to just add it straight to $data? Less chance of old data being reused. Added a patch that goes that route.

Ups :)

RC eligible because there are just test changes.

Committed ec438eb and pushed to 8.0.x. Thanks!

phpunit modules/views/tests/src/Unit/Plugin/argument_default/QueryParameterTest.php --tap
TAP version 13
ok 1 - Drupal\Tests\views\Unit\Plugin\argument_default\QueryParameterTest::testGetArgument with data set #0 (array('test'), Symfony\Component\HttpFoundation\Request Object (...), 'data')
ok 2 - Drupal\Tests\views\Unit\Plugin\argument_default\QueryParameterTest::testGetArgument with data set #1 (array('test', 'and'), Symfony\Component\HttpFoundation\Request Object (...), 'data1,data2')
ok 3 - Drupal\Tests\views\Unit\Plugin\argument_default\QueryParameterTest::testGetArgument with data set #2 (array('test', 'or'), Symfony\Component\HttpFoundation\Request Object (...), 'data1+data2')
ok 4 - Drupal\Tests\views\Unit\Plugin\argument_default\QueryParameterTest::testGetArgument with data set #3 (array('test', 'blub'), Symfony\Component\HttpFoundation\Request Object (...), 'blub')
1..4

This looks much better.. nice catch.