CI: Run Ruby 2.x in docker (#1618)

Author: lsegal

.github/workflows/ci.yml

@@ -5,23 +5,45 @@ jobs:
   build:
     name: "Ruby: ${{ matrix.ruby }} OS: ${{ matrix.os }}"
     runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         # 3.0 is interpreted as 3
         ruby: ["3.0", 3.1, 3.2, 3.3, 3.4]
-        exclude:
-          - { os: windows-latest, ruby: 2.2 }
-          - { os: windows-latest, ruby: 2.3 }
+        include:
+          - os: ubuntu-latest
+            container: ruby:2.2
+            ruby: 2.2
+          - os: ubuntu-latest
+            container: ruby:2.3
+            ruby: 2.3
+          - os: ubuntu-latest
+            container: ruby:2.4
+            ruby: 2.4
+          - os: ubuntu-latest
+            container: ruby:2.5
+            ruby: 2.5
+          - os: ubuntu-latest
+            container: ruby:2.6
+            ruby: 2.6
+          - os: ubuntu-latest
+            container: ruby:2.7
+            ruby: 2.7
+
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v1
       - name: Install Ruby & 'bundle install'
+        if: matrix.container == null
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
+      - name: Bundle install
+        if: matrix.container != null
+        run: bundle install --jobs=4 --retry=3
       - name: Run Test
         run: |
           ruby -v

spec/spec_helper.rb

@@ -27,7 +27,7 @@ def self.parser_type; @parser_type == :ruby ? :ruby18 : @parser_type end
 begin
   require 'coveralls'
   Coveralls.wear!
-end if ENV['CI'] && HAVE_RIPPER
+end if ENV['CI'] && HAVE_RIPPER && RUBY_VERSION >= '2.5.0'
 
 NAMED_OPTIONAL_ARGUMENTS = RUBY_VERSION >= '2.1.0'