Test the gem with Jekyll versions 3 and 4

.gitignore

@@ -1,5 +1,5 @@
 /*.gem
 /.bundle/
-/Gemfile.lock
-/node_modules/
+/test/fixture/site/.jekyll-cache/
 /test/fixture/site/_site/
+/vendor/

.travis.yml

@@ -7,6 +7,13 @@ rvm:
   - 2.5.7
   - 2.6.5
   - 2.7.0
+gemfile:
+  - Gemfile-jekyll3
+  - Gemfile-jekyll4
+jobs:
+  exclude:
+    - rvm: 2.3.8
+      gemfile: Gemfile-jekyll4
 before_install:
   - "echo 'gem: --no-document' > ~/.gemrc"
   - gem update bundler

DEVELOPMENT.md

@@ -0,0 +1,32 @@
+# Development
+
+Use [Bundler] to install project dependencies. Because we support Jekyll
+versions 3 and 4, we have separate [Gemfiles][BundlerGemfile] for
+installing dependencies:
+
+* [Gemfile-jekyll3](Gemfile-jekyll3) for Jekyll 3
+* [Gemfile-jekyll3](Gemfile-jekyll4) for Jekyll 4
+
+Install dependencies for the selected Gemfile:
+
+``` shell
+BUNDLE_GEMFILE=Gemfile-jekyll4 bundle install
+```
+
+Use the [Rakefile](Rakefile) to run common tasks. To see the tasks
+available:
+
+``` shell
+BUNDLE_GEMFILE=Gemfile-jekyll4 bundle exec rake -D
+```
+
+Run linter ([Rubocop]) and tests:
+
+``` shell
+BUNDLE_GEMFILE=Gemfile-jekyll4 bundle exec rake
+```
+
+[BundlerGemfile]: https://bundler.io/v2.0/man/gemfile.5.html
+[Bundler]: https://bundler.io/
+[Jekyll]: https://jekyllrb.com/
+[Rubocop]: https://docs.rubocop.org/en/stable/

Gemfile → Gemfile-jekyll3

@@ -1,4 +1,9 @@
 # frozen_string_literal: true
 
 source 'https://rubygems.org/'
+
 gemspec
+
+group :development do
+  gem 'jekyll', '~> 3.0'
+end

Gemfile-jekyll3.lock

@@ -0,0 +1,101 @@
+PATH
+  remote: .
+  specs:
+    jekyll-minibundle (2.2.0)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    ast (2.4.0)
+    benchmark-ips (2.7.2)
+    coderay (1.1.2)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.6)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.12.2)
+    forwardable-extended (2.6.0)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jaro_winkler (1.5.4)
+    jekyll (3.8.6)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 1.14)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (>= 1.7, < 4)
+      safe_yaml (~> 1.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (1.17.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.3.6)
+    method_source (0.9.2)
+    mini_portile2 (2.4.0)
+    minitest (5.14.0)
+    nokogiri (1.10.8)
+      mini_portile2 (~> 2.4.0)
+    parallel (1.19.1)
+    parser (2.7.0.3)
+      ast (~> 2.4.0)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    pry (0.12.2)
+      coderay (~> 1.1.0)
+      method_source (~> 0.9.0)
+    public_suffix (4.0.3)
+    rainbow (3.0.0)
+    rake (13.0.1)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.16.0)
+    rubocop (0.80.1)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.7.0.1)
+      rainbow (>= 2.2.2, < 4.0)
+      rexml
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 1.7)
+    ruby-progressbar (1.10.1)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    unicode-display_width (1.6.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  benchmark-ips (~> 2.7)
+  jekyll (~> 3.0)
+  jekyll-minibundle!
+  minitest (~> 5.8)
+  nokogiri (~> 1.6)
+  pry (~> 0.10)
+  rake (~> 13.0)
+  rubocop (~> 0.80.1)
+
+BUNDLED WITH
+   2.1.4

Gemfile-jekyll4

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org/'
+
+gemspec
+
+group :development do
+  gem 'jekyll', '~> 4.0'
+end

Gemfile-jekyll4.lock

@@ -0,0 +1,104 @@
+PATH
+  remote: .
+  specs:
+    jekyll-minibundle (2.2.0)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    ast (2.4.0)
+    benchmark-ips (2.7.2)
+    coderay (1.1.2)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.6)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.12.2)
+    forwardable-extended (2.6.0)
+    http_parser.rb (0.6.0)
+    i18n (1.8.2)
+      concurrent-ruby (~> 1.0)
+    jaro_winkler (1.5.4)
+    jekyll (4.0.0)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (>= 0.9.5, < 2)
+      jekyll-sass-converter (~> 2.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 2.1)
+      kramdown-parser-gfm (~> 1.0)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (~> 3.0)
+      safe_yaml (~> 1.0)
+      terminal-table (~> 1.8)
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (2.1.0)
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.3.6)
+    method_source (0.9.2)
+    mini_portile2 (2.4.0)
+    minitest (5.14.0)
+    nokogiri (1.10.8)
+      mini_portile2 (~> 2.4.0)
+    parallel (1.19.1)
+    parser (2.7.0.3)
+      ast (~> 2.4.0)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    pry (0.12.2)
+      coderay (~> 1.1.0)
+      method_source (~> 0.9.0)
+    public_suffix (4.0.3)
+    rainbow (3.0.0)
+    rake (13.0.1)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.16.0)
+    rubocop (0.80.1)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.7.0.1)
+      rainbow (>= 2.2.2, < 4.0)
+      rexml
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 1.7)
+    ruby-progressbar (1.10.1)
+    safe_yaml (1.0.5)
+    sassc (2.2.1)
+      ffi (~> 1.9)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    unicode-display_width (1.6.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  benchmark-ips (~> 2.7)
+  jekyll (~> 4.0)
+  jekyll-minibundle!
+  minitest (~> 5.8)
+  nokogiri (~> 1.6)
+  pry (~> 0.10)
+  rake (~> 13.0)
+  rubocop (~> 0.80.1)
+
+BUNDLED WITH
+   2.1.4

README.md

@@ -11,8 +11,8 @@ cache busting.
 There are no runtime dependencies, except for the minification tool used
 for bundling (fingerprinting has no dependencies).
 
-The plugin requires Jekyll version 3.x. It is tested with Ruby MRI 2.3
-and later. Ruby 1.8 and 1.9 are *not* supported.
+The plugin requires Jekyll version 3 or 4. It is tested with Ruby MRI
+2.3 and later.
 
 The plugin works with Jekyll's watch mode (auto-regeneration, Jekyll
 option `--watch`), but not with incremental feature enabled (Jekyll

Rakefile

@@ -79,13 +79,14 @@ task :test do
 
   extra_opts = ENV['DEBUG'] ? '-w -rpp -rpry ' : ''
 
+  puts "Jekyll version: #{Gem::Specification.find_by_name('jekyll').version}"
   sh "ruby -I lib:test #{extra_opts}#{run_selected_or_all}"
 end
 
 namespace :fixture do
   CLEAN.include 'test/fixture/site/_site'
 
-  desc 'Generate fixture site'
+  desc 'Generate fixture site (tests use it, this task allows manual inspection)'
   task :build do
     run_jekyll_in_fixture_site('build')
   end