run tests using GitHub actions

.github/workflows/unit-tests.yaml

@@ -0,0 +1,37 @@
+on:
+    - push
+    - pull_request
+
+jobs:
+    phpunit:
+        runs-on: ubuntu-latest
+
+        strategy:
+            matrix:
+                include:
+                    - '7.1'
+                    - '7.2'
+                    - '7.3'
+                    - '7.4'
+                    - '8.0'
+                    - '8.1'
+                    - '8.2'
+                    - '8.3'
+                    - '8.4'
+
+        steps:
+            - name: Checkout the source code
+              uses: actions/checkout@v4
+
+            - name: Set up PHP
+              uses: shivammathur/setup-php@v2
+              with:
+                  php-version: '${{ matrix.php }}'
+
+            - name: Install dependencies
+              run: composer install
+
+            - name: Run tests
+              run: |
+                  vendor/bin/phpunit
+                  vendor/bin/phpunit test/CommonMarkTestWeak.php || true

.travis.yml

@@ -1,28 +0,0 @@
-language: php
-
-dist: trusty
-sudo: false
-
-matrix:
-  include:
-    - php: 5.3
-      dist: precise
-    - php: 5.4
-    - php: 5.5
-    - php: 5.6
-    - php: 7.0
-    - php: 7.1
-    - php: 7.2
-    - php: 7.3
-    - php: nightly
-  fast_finish: true
-  allow_failures:
-    - php: nightly
-
-install:
-  - composer install --prefer-dist --no-interaction --no-progress
-
-script:
-  - vendor/bin/phpunit
-  - vendor/bin/phpunit test/CommonMarkTestWeak.php || true
-  - '[ -z "$TRAVIS_TAG" ] || [ "$TRAVIS_TAG" == "$(php -r "require(\"Parsedown.php\"); echo Parsedown::version;")" ]'

test/CommonMarkTestStrict.php

@@ -1,11 +1,13 @@
 <?php
 
+use PHPUnit\Framework\TestCase;
+
 /**
  * Test Parsedown against the CommonMark spec
  *
  * @link http://commonmark.org/ CommonMark
  */
-class CommonMarkTestStrict extends PHPUnit_Framework_TestCase
+class CommonMarkTestStrict extends TestCase
 {
     const SPEC_URL = 'https://raw.githubusercontent.com/jgm/CommonMark/master/spec.txt';