Introduce GitHub Actions.

Author: simi

.github/workflows/test.yml

@@ -0,0 +1,32 @@
+name: Tests
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-18.04
+    strategy:
+      matrix:
+        ruby_version: ['3.1', '3.0', '2.7']
+        rails_version: ['6.0.x', '6.1.x', '7.0.x', 'edge']
+    name: Ruby ${{ matrix.ruby_version }} on Rails ${{ matrix.rails_version }}
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/Gemfile-rails.${{ matrix.rails_version }}
+    steps:
+    - name: Install graphviz
+      run: |
+        sudo apt-get update -qq
+        sudo apt-get install -qq graphviz
+    - uses: actions/checkout@v3
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby_version }}
+        bundler-cache: true
+    - name: Run tests
+      run: |
+        bundle exec rake test