$this->drupalGet('admin/config/media/responsive-image-style/style_one/delete');
$this->drupalPostForm(NULL, [], t('Delete'));
$this->drupalGet('admin/config/media/responsive-image-style');
$this->drupalGet('admin/config/media/responsive-image-style/style_one/delete');
$this->drupalPostForm(NULL, [], t('Delete'));
$this->drupalGet('admin/config/media/responsive-image-style');