Adjust gemspec to allow use with Jekyll 4.0 (#492)

* Allow use with Jekyll 4.0
* Allow testing with specific Jekyll versions

Author: zocoi

.gitignore

@@ -1,5 +1,6 @@
 _site/
 .gems/
+.jekyll-cache/
 .sass-cache/
 .jekyll-metadata
 /.bundle/

.travis.yml

@@ -13,7 +13,8 @@ cache:
 env:
   matrix:
     - TEST_SUITE=node
-    - TEST_SUITE=ruby
+    - TEST_SUITE=ruby JEKYLL_VERSION="~> 3.8"
+    - TEST_SUITE=ruby JEKYLL_VERSION="~> 4.0"
 after_success:
   - npm run test:cover:CI
 branches:

Gemfile

@@ -1,8 +1,11 @@
 source "https://rubygems.org"
 
-# Specify your gem's dependencies in jekyll-admin.gemspec
+# Specify the gem's dependencies in jekyll-admin.gemspec
 gemspec
 
+# To allow testing with specific Jekyll versions
+gem "jekyll", ENV["JEKYLL_VERSION"] if ENV["JEKYLL_VERSION"]
+
 # Site dependencies
 gem "jekyll-seo-tag"
 gem "jekyll-sitemap"

jekyll-admin.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r!^exe/!) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "jekyll", "~> 3.3"
+  spec.add_dependency "jekyll", ">= 3.3", "< 5.0"
   spec.add_dependency "sinatra", "~> 1.4"
   spec.add_dependency "sinatra-contrib", "~> 1.4"