Run CI in GitHub Actions

.github/workflows/push.yml

@@ -0,0 +1,19 @@
+on: push
+name: cibuild on push
+jobs:
+  build:
+    name: "GitHub Pages Tests"
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby:
+          - 2.3
+          - 2.4
+          - 2.5
+          - 2.6
+    steps:
+    - uses: actions/checkout@master
+    - name: script/cibuild-docker
+      run: script/cibuild-docker
+      with:
+        ruby_version: ${{ matrix.ruby }}

Dockerfile

@@ -1,4 +1,5 @@
-FROM ruby:2.5.3
+ARG RUBY_VERSION
+FROM ruby:$RUBY_VERSION
 
 RUN apt-get update \
   && apt-get install -y \
@@ -7,11 +8,15 @@ RUN apt-get update \
     make \
     nodejs
 
-COPY . /src/gh/pages-gem
+COPY Gemfile* /src/gh/pages-gem/
+COPY github-pages.gemspec /src/gh/pages-gem
+COPY lib/ /src/gh/pages-gem/lib
 
 RUN \
   bundle config local.github-pages /src/gh/pages-gem && \
-  bundle install --gemfile=/src/gh/pages-gem/Gemfile
+  NOKOGIRI_USE_SYSTEM_LIBRARIES=true bundle install --gemfile=/src/gh/pages-gem/Gemfile
+
+COPY . /src/gh/pages-gem
 
 RUN \
   echo "en_US UTF-8" > /etc/locale.gen && \

script/cibuild

@@ -6,7 +6,7 @@ set -e
 echo "Jekyll version: $(bundle exec jekyll --version)"
 
 echo "Running Ruby tests..."
-bundle exec rspec
+bundle exec rspec --format documentation
 
 echo "Running Ruby style tests..."
 script/fmt --display-style-guide

script/cibuild-docker

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+set -ex
+
+# Set the ruby version in the Action definition matrix.
+RUBY_VERSION="$INPUT_RUBY_VERSION"
+: "${RUBY_VERSION:="2.5.3"}"
+
+docker build --build-arg "RUBY_VERSION=$RUBY_VERSION" -t github-pages .
+docker run --rm --workdir /src/gh/pages-gem github-pages script/cibuild