Tests machine name controller's transliteration functionality.
@dataProvider providerTestMachineNameController
array $request_params: An array of request parameters.
$expected_content: The expected content of the JSONresponse.
\Drupal\system\MachineNameController::transliterate()
public function testMachineNameController(array $request_params, $expected_content) {
$request = Request::create('', 'GET', $request_params);
$json = $this->machineNameController
->transliterate($request);
$this
->assertEquals($expected_content, $json
->getContent());
}