MDL-70276 github actions: First cut, phpunit and grunt checks

First working version, supports phpunit (using build matrix):

- php72 (lowest), running mysql.
- php74 (highest), running postgres.

Also verifies that the branch has been "gruntified" and there
isn't any missing change (build js/css files).

TODO: Verify the remaining checks currently in .travis.yml, namely:
 - CITEST
 - Add caching
 - Better health-check for DB images.
 - Support from the tracker (satus badges and enable check).
 - Support from CiBoT (status and enable check).
 - Consider moving both the common setup (git, composer...)
   and the database (mysql, postgres) to own actions for
   easier tweaking.

.github/workflows/config-template.php

@@ -0,0 +1,71 @@
+<?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/>.
+
+/**
+ * Template configuraton file for github actions CI/CD.
+ *
+ * @package    core
+ * @copyright  2020 onwards Eloy Lafuente (stronk7) {@link https://stronk7.com}
+ * @license    https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+// This cannot be used out from a github actions workflow, so just exit.
+getenv('GITHUB_WORKFLOW') || die; // phpcs:ignore moodle.Files.MoodleInternal.MoodleInternalGlobalState
+
+unset($CFG);
+global $CFG;
+$CFG = new stdClass();
+
+$CFG->dbtype    = getenv('dbtype');
+$CFG->dblibrary = 'native';
+$CFG->dbhost    = '127.0.0.1';
+$CFG->dbname    = 'test';
+$CFG->dbuser    = 'test';
+$CFG->dbpass    = 'test';
+$CFG->prefix    = 'm_';
+$CFG->dboptions = ['dbcollation' => 'utf8mb4_bin'];
+
+$host = 'localhost';
+$CFG->wwwroot   = "http://{$host}";
+$CFG->dataroot  = realpath(dirname(__DIR__)) . '/moodledata';
+$CFG->admin     = 'admin';
+$CFG->directorypermissions = 0777;
+
+// Debug options - possible to be controlled by flag in future.
+$CFG->debug = (E_ALL | E_STRICT); // DEBUG_DEVELOPER.
+$CFG->debugdisplay = 1;
+$CFG->debugstringids = 1; // Add strings=1 to url to get string ids.
+$CFG->perfdebug = 15;
+$CFG->debugpageinfo = 1;
+$CFG->allowthemechangeonurl = 1;
+$CFG->passwordpolicy = 0;
+$CFG->cronclionly = 0;
+$CFG->pathtophp = getenv('pathtophp');
+
+$CFG->phpunit_dataroot  = realpath(dirname(__DIR__)) . '/phpunitdata';
+$CFG->phpunit_prefix = 't_';
+
+define('TEST_EXTERNAL_FILES_HTTP_URL', 'http://localhost:8080');
+define('TEST_EXTERNAL_FILES_HTTPS_URL', 'http://localhost:8080');
+
+define('TEST_SESSION_REDIS_HOST', 'localhost');
+define('TEST_CACHESTORE_REDIS_TESTSERVERS', 'localhost');
+
+// TODO: add others (solr, mongodb, memcached, ldap...).
+
+// Too much for now: define('PHPUNIT_LONGTEST', true); // Only leaves a few tests out and they are run later by CI.
+
+require_once(__DIR__ . '/lib/setup.php');

.github/workflows/push.yml

@@ -0,0 +1,103 @@
+name: Core
+
+on: [push]
+
+env:
+  php: 7.4
+
+jobs:
+  Grunt:
+    runs-on: ubuntu-18.04
+
+    steps:
+      - name: Checking out code
+        uses: actions/checkout@v2
+
+      - name: Configuring node & npm
+        shell: bash -l {0}
+        run: nvm install
+
+      - name: Installing node stuff
+        run: npm install
+
+      - name: Running grunt
+        run: npx grunt
+
+      - name: Looking for uncommitted changes
+        # Add all files to the git index and then run diff --cached to see all changes.
+        # This ensures that we get the status of all files, including new files.
+        # We ignore npm-shrinkwrap.json to make the tasks immune to npm changes.
+        run: |
+          git add .
+          git reset -- npm-shrinkwrap.json
+          git diff --cached --exit-code
+
+  PHPUnit:
+    runs-on: ${{ matrix.os }}
+    services:
+      exttests:
+        image: moodlehq/moodle-exttests
+        ports:
+          - 8080:80
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-18.04
+            php: 7.2
+            db: mysqli
+          - os: ubuntu-18.04
+            php: 7.4
+            db: pgsql
+
+    steps:
+      - name: Setting up DB mysql
+        if: ${{ matrix.db == 'mysqli' }}
+        uses: johanmeiring/mysql-action@tmpfs-patch
+        with:
+          collation server: utf8mb4_bin
+          mysql version: 5.7
+          mysql database: test
+          mysql user: test
+          mysql password: test
+          use tmpfs: true
+
+      - name: Setting up DB pgsql
+        if: ${{ matrix.db == 'pgsql' }}
+        uses: m4nu56/postgresql-action@v1
+        with:
+          postgresql version: 9.6
+          postgresql db: test
+          postgresql user: test
+          postgresql password: test
+
+      - name: Configuring git vars
+        uses: rlespinasse/github-slug-action@v3.x
+
+      - name: Setting up PHP ${{ matrix.php }}
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+
+      - name: Checking out code from ${{ env.GITHUB_REF_SLUG }}
+        uses: actions/checkout@v2
+
+      - name: Setting up PHPUnit
+        env:
+          dbtype: ${{ matrix.db }}
+        run: |
+          echo "pathtophp=$(which php)" >> $GITHUB_ENV # Inject installed pathtophp to env. The template config needs it.
+          cp .github/workflows/config-template.php config.php
+          mkdir ../moodledata
+          sudo locale-gen en_AU.UTF-8
+          php admin/tool/phpunit/cli/init.php --no-composer-self-update
+
+      - name: Running PHPUnit tests
+        env:
+          dbtype: ${{ matrix.db }}
+        run: vendor/bin/phpunit -v