Fix SimpletestPhpunitRunCommandTest

Problem/Motivation

In #2641632-4: Refactor simpletest's *_phpunit_*() (and junit) functions etc. to a class, deprecate I discovered a bug in SimpletestPhpunitRunCommandTest.

SimpletestPhpunitRunCommandTest, which I have to say is a super-awesome great test to have, is full of bugs.

It looks like this:

function testSimpletestPhpUnitRunCommand() {
  include_once __DIR__ . '/../../fixtures/simpletest_phpunit_run_command_test.php';
  $app_root = __DIR__ . '/../../../../../..';
  include_once "$app_root/core/modules/simpletest/simpletest.module";
  $container = new ContainerBuilder;
  $container->set('app.root', $app_root);
  $file_system = $this->prophesize('Drupal\Core\File\FileSystemInterface');
  $file_system->realpath('public://simpletest')->willReturn(sys_get_temp_dir());
  $container->set('file_system', $file_system->reveal());
  \Drupal::setContainer($container);
  $test_id = basename(tempnam(sys_get_temp_dir(), 'xxx'));
  foreach (['pass', 'fail'] as $status) {
    putenv('SimpletestPhpunitRunCommandTestWillDie=' . $status);
    $ret = simpletest_run_phpunit_tests($test_id, ['Drupal\Tests\simpletest\Unit\SimpletestPhpunitRunCommandTestWillDie']);
    $this->assertSame($ret[0]['status'], $status);
  }
  unlink(simpletest_phpunit_xml_filepath($test_id));
}

It sets the file_system service to deal with the temp file directory, which is good.

Then it generates a temp file and uses its name as the test id, which is bad, because the test id is supposed to be an integer, and now we have an unneeded file in tmp.

It also uses the same id for two test runs, which means the files will overwrite themselves and thus we lose the benefit of expecting that two files will be generated.

Proposed resolution

Remove the need for an extraneous temp file which is never deleted.

Change the test ID to be an integer.

Remove the two test results files as part of the test.

Remaining tasks

User interface changes

API changes

Data model changes