Unit Testing

Unit tests are the best way of checking the behaviour of your external services and can help you to:

• 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

Writing unit tests for an external service function is no different to writing unit tests for any other part of Moodle, which is documented in under PHPUnit.

How to write an external function PHPUnit test

You should create one unit test testcase for each external service file, and it should be named after the file that it tests.

For example, if you have written a service function in [componentfolder]/classes/external/get_fruit.php, you should write a unit test in [componentfolder]/tests/external/get_fruit_test.php.

mod/kitchen/tests/external/get_fruit_test.php

<?php
// 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
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// 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/>.

/**
 * Unit tests for the get_fruit function of the kitchen.
 *
 * @package    mod_kitchen
 * @category   external
 * @copyright  20XX Your Name
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace mod_kitchen\external;

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

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

class get_fruit_test extends externallib_advanced_testcase {

    /**
     * Test the execute function when capabilities are present.
     *
     * @covers \mod_fruit\external\get_fruit::execute
     */
    public function test_capabilities(): void {
        $this->resetAfterTest(true);

        $course = $this->getDataGenerator()->create_course();
        $cm = $this->getDataGenerator()->create_module('mod_kitchen', [
            'course' => $course->id,
        ]);

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

        // Call the external service function.
        $returnvalue = get_fruit::execute([
            'course' => $course->id,
            'cmid' => $cm->id,
        ]);

        // We need to execute the return values cleaning process to simulate
        // the web service server.
        $returnvalue = \core_external\external_api::clean_returnvalue(
            get_fruit::execute_returns(),
            $returnvalue
        );

        // Assert that there was a response.
        // The actual response is tested in other tests.
        $this->assertNotNull($returnvalue);
    }

    /**
     * Test the execute function when capabilities are missing.
     *
     * @covers \mod_fruit\external\get_fruit::execute
     */
    public function test_capabilities_missing(): void {
        global $USER;

        $this->resetAfterTest(true);

        $course = $this->getDataGenerator()->create_course();
        $cm = $this->getDataGenerator()->create_module('mod_kitchen', [
            'course' => $course->id,
        ]);

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

        $params = [PARAM1, PARAM2, ...];

        // Call without required capability
        $this->expectException(required_capability_exception::class);
        get_fruit::execute([
            'course' => $course->id,
            'cmid' => $cm->id,
        ]);
    }
}