start using actions with a dummy module

This way, we can actually show how it works in practice.

Author: mvdan

.github/workflows/test.yml

@@ -0,0 +1,18 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.12.9, 1.13]
+        platform: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.platform }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v1
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v1
+    - name: Test
+      run: go test ./...

README.md

@@ -2,7 +2,8 @@
 
 [GitHub Actions](https://github.com/features/actions) includes CI/CD for free
 for Open Source repositories. This document contains information on making it
-work well for [Go](https://github.com/features/actions).
+work well for [Go](https://github.com/features/actions). See them [in
+action](https://github.com/mvdan/github-actions-golang/actions):
 
 ```
 $ cat .github/workflows/test.yml

actions.go

@@ -0,0 +1,15 @@
+// Copyright (c) 2019, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package actions
+
+import (
+	"fmt"
+	"runtime"
+)
+
+func Demo() {
+	fmt.Printf("Go version: %s\n", runtime.Version())
+	fmt.Printf("GOOS: %s\n", runtime.GOOS)
+	fmt.Printf("GOARCH: %s\n", runtime.GOARCH)
+}

actions_test.go

@@ -0,0 +1,12 @@
+// Copyright (c) 2019, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package actions
+
+import (
+	"testing"
+)
+
+func TestDemo(t *testing.T) {
+	Demo()
+}

go.mod

@@ -0,0 +1,3 @@
+module dummy.module/actions
+
+go 1.13