Enable testing for Windows platform

Gemfile

@@ -4,3 +4,8 @@ source "https://rubygems.org"
 gemspec
 
 gem "jekyll", "~> #{ENV["JEKYLL_VERSION"]}" if ENV["JEKYLL_VERSION"]
+
+install_if -> { Gem.win_platform? } do
+  gem "tzinfo", "~> 1.2"
+  gem "tzinfo-data"
+end

appveyor.yml

@@ -0,0 +1,23 @@
+version: "{build}"
+clone_depth: 5
+build: off
+
+environment:
+  NOKOGIRI_USE_SYSTEM_LIBRARIES: true
+  matrix:
+    - RUBY_FOLDER_VER: "26"
+    - RUBY_FOLDER_VER: "24"
+
+install:
+  - SET PATH=C:\Ruby%RUBY_FOLDER_VER%-x64\bin;%PATH%
+  - bundle install --retry 5 --jobs=%NUMBER_OF_PROCESSORS% --clean --path vendor\bundle
+
+test_script:
+  - ruby --version
+  - gem --version
+  - bundler --version
+  - bash ./script/test
+
+cache:
+  # If one of the files after the right arrow changes, cache will be invalidated
+  - 'vendor\bundle -> appveyor.yml, Gemfile, jekyll-feed.gemspec'

spec/jekyll-feed_spec.rb

@@ -205,6 +205,7 @@
 
   context "validation" do
     it "validates" do
+      skip "Typhoeus couldn't find the 'libcurl' module on Windows" if Gem.win_platform?
       # See https://validator.w3.org/docs/api.html
       url = "https://validator.w3.org/feed/check.cgi?output=soap12"
       response = Typhoeus.post(url, :body => { :rawdata => contents }, :accept_encoding => "gzip")

spec/spec_helper.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "jekyll"
-require "typhoeus"
+require "typhoeus" unless Gem.win_platform?
 require "nokogiri"
 require "rss"
 require File.expand_path("../lib/jekyll-feed", __dir__)