Delete translation files after deleting a language.
function testDeleteLanguage() {
$langcode = 'de';
$this
->addLanguage($langcode);
$file_uri = 'translations://po_' . $this
->randomName() . '.' . $langcode . '.po';
file_put_contents(drupal_realpath($file_uri), $this
->randomName());
$this
->assertTrue(is_file($file_uri), 'Translation file is created.');
language_delete($langcode);
$this
->assertTrue($file_uri);
$this
->assertFalse(is_file($file_uri), 'Translation file deleted after deleting language');
}