Run tests on GitHub Actions

Travis CI does not offer free minutes for open source projects. GitHub Actions ha sbetter integration with GitHub. Migrating does require dropping Ruby 1.9 and 2.0 from CI matrix, but these have not been maintained for years now.

.github/workflows/ruby.yml

@@ -1,8 +1,45 @@
-name: Ruby
+name: CI
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
+  test:
+    name: >-
+      Test (${{ matrix.ruby }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        gemfile: [Gemfile]
+        ruby:
+          - "2.1"
+          - "2.2"
+          - "2.3"
+          - "2.4"
+          - "2.5"
+          - "2.6"
+          - "2.7"
+          - "3.0"
+          - jruby
+          - truffleruby
+        include:
+          - ruby: 2.5
+            gemfile: gemfiles/rubyracer
+          - ruby: jruby
+            gemfile: gemfiles/rubyrhino
+          - ruby: 2.5
+            gemfile: gemfiles/alaska
+            alaska: 1
+    env:
+      BUNDLE_GEMFILE: ${{ matrix.gemfile }}
+      ALASKA: ${{ matrix.alaska}}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - run: bundle exec rake spec
   lint:
     runs-on: ubuntu-latest
 

README.md

@@ -7,8 +7,6 @@ UglifyJS currently is extensively tested with ES5, but also includes experimenta
 
 More stable alternatives for working with ES6 code is to first transpile to ES5 with e.g. [babel-transpiler](https://github.com/babel/ruby-babel-transpiler) or using [Closure Compiler](https://github.com/documentcloud/closure-compiler) to directly minify ES6 code.
 
-[![Build Status](https://travis-ci.org/lautis/uglifier.svg?branch=master)](https://travis-ci.org/lautis/uglifier)
-
 ## ES6 / ES2015+ / Harmony mode
 
 When using Uglifier with ES6 syntax without any options, an error will be

spec/spec_helper.rb

@@ -8,7 +8,7 @@
 # in ./support/ and its subdirectories.
 Dir["#{File.dirname(__FILE__)}/support/**/*.rb"].each { |f| require f }
 
-if ENV["ALASKA"]
+if ENV["ALASKA"] == "1"
   require 'alaska/runtime'
   require 'tempfile'
   ExecJS.runtime = Alaska::Runtime.new