User warning about missing data thrown when running tests using simpletest.

The following warning is thrown when running tests that visit search pages with facets.
User warning: Attempting to perform token replacement for token type facetapi_results without required data in token_tokens() line 912 of contrib/token/token.tokens.inc.

To replicate this error on an actual site, comment out the lines that check whether you're running a test in token.tokens.inc of the token module:

// if (!empty($GLOBALS['drupal_test_info']['test_run_id'])) {
    // Only check when tests are running.
    $type_info = token_get_info($type);
    if (!empty($type_info['needs-data']) && !isset($data[$type_info['needs-data']])) {
      trigger_error(t('Attempting to perform token replacement for token type %type without required data', array('%type' => $type)), E_USER_WARNING);
    }
//  }

And navigate to a search page with facet.