Setup GitHub Actions CI

Try to setup GitHub Actions CI.

.github/workflows/tests.yml

@@ -0,0 +1,39 @@
+name: GitHub Actions CI
+on: [push]
+jobs:
+  tests:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest]
+
+    steps:
+    - name: Set up Git repository
+      uses: actions/checkout@master
+
+    - name: Reset system Homebrew installation
+      run: brew update-reset
+      if: matrix.os == 'macOS-latest'
+
+    - name: Check Ruby style
+      run: brew style homebrew/bundle
+      if: matrix.os == 'macOS-latest'
+
+    - name: Set up Ruby
+      uses: actions/setup-ruby@v1
+      with:
+        version: '>=2.3'
+      if: matrix.os == 'ubuntu-latest'
+
+    - name: Environment dump
+      run: env
+
+    - name: Install RubyGems
+      run: |
+        gem install bundler
+        bundle install --jobs 4 --retry 3
+
+    - name: Run RSpec tests
+      run: bundle exec rspec
+      env:
+        COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}

spec/spec_helper.rb

@@ -36,21 +36,18 @@ def linux?
 
 formatters = [SimpleCov::Formatter::HTMLFormatter]
 
-# Coveralls in Azure Pipelines
-if ENV["COVERALLS_REPO_TOKEN"] && ENV["TF_BUILD"]
+if macos? && ENV["COVERALLS_REPO_TOKEN"]
   require "coveralls"
 
   formatters << Coveralls::SimpleCov::Formatter
 
   ENV["CI"] = "1"
-  ENV["CI_NAME"] = "azure-pipelines"
-  ENV["CI_BUILD_NUMBER"] = ENV["BUILD_BUILDID"]
-  ENV["CI_BUILD_URL"] = "#{ENV["SYSTEM_TEAMFOUNDATIONSERVERURI"]}#{ENV["SYSTEM_TEAMPROJECT"]}/_build/results?buildId=#{ENV["BUILD_BUILDID"]}"
-  ENV["CI_BRANCH"] = ENV["BUILD_SOURCEBRANCH"]
-  ENV["CI_PULL_REQUEST"] = ENV["SYSTEM_PULLREQUEST_PULLREQUESTNUMBER"]
-
-  require "simplecov-cobertura"
-  formatters << SimpleCov::Formatter::CoberturaFormatter
+  ENV["CI_NAME"] = "github-actions"
+  ENV["CI_BUILD_NUMBER"] = ENV["RUNNER_TRACKING_ID"]
+  ENV["CI_BRANCH"] = ENV["GITHUB_REF"]
+  # TODO: fill out values when more env vars available.
+  # ENV["CI_BUILD_URL"] =
+  # ENV["CI_PULL_REQUEST"] = ENV["SYSTEM_PULLREQUEST_PULLREQUESTNUMBER"]
 end
 
 SimpleCov.formatters = SimpleCov::Formatter::MultiFormatter.new(formatters)