Web Services Unit Test

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Moodle 2.3 Since Moodle 2.3 we are using PHP Unit framework. Writing a unit test before writing an external function will end up to be very helpful. The easiest external function is not an easy task, as you can see in How to contribute a web service function to core. When writing PHPUnit tests you will:

  • discover use cases you didn't think about.
  • understand the feelings and the needs of the web service client developer.
  • end up with a function usable by everybody, not only by your own client.
  • reach integration way faster as you joined a proof of validity
  • make the QA process a breeze

How to run a PHPUnit test

you should read first the PHPUnit Moodle documentation to have a grasp of PHPUnit in Moodle.

How to write an external function PHPUnit test

If it doesn't exist create a COMPONENTFOLDER/tests/externallib_test.php file.

// This file is part of Moodle - http://moodle.org/
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

 * COMPONENT External functions unit tests
 * @package    core_component
 * @category   external
 * @copyright  20XX Your Name
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

defined('MOODLE_INTERNAL') || die();

require_once($CFG->dirroot . '/webservice/tests/helpers.php');
require_once($CFG->dirroot . '/COMPONENT/externallib.php');

class COMPONENT_external_testcase extends externallib_advanced_testcase {

     * Test
    public function test_FUNCTION_NAME() {
        global $USER;


        // Set the required capabilities by the external function
        $contextid = context_XXXX::instance()->id;
        $roleid = $this->assignUserCapability('moodle/CAPABILITYNAME', $contextid);

        $params = array(PARAM1, PARAM2, ...);

        $returnvalue = COMPONENT_external::FUNCTION_NAME($params);

        // We need to execute the return values cleaning process to simulate the web service server
        $returnvalue = external_api::clean_returnvalue(COMPONENT_external::FUNCTION_NAME_returns(), $returnvalue);

        // Some PHPUnit assert
        $this->assertEquals(EXPECTED_VALUE, RETURNED_VALUE);

        // Call without required capability
        $this->unassignUserCapability('moodle/CAPABILITYNAME', $contextid, $roleid);
        $returnvalue = COMPONENT_external::FUNCTION_NAME($params);


But the quickest way is most likely to look at some example like course/tests/courseexternallib_test.php - get_categories (MDL-33995). Also read Writing PHPUnit tests.

Coding style

  • external functions often check many capabilities. Remember to assign the correct one to the $USER and also test for exception when the $USER doesn't have them.