Simulate last_modified_at injection by plugin (#256)

Merge pull request 256

jekyll-sitemap.gemspec

@@ -23,7 +23,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency "jekyll", ">= 3.7", "< 5.0"
 
   spec.add_development_dependency "bundler"
-  spec.add_development_dependency "jekyll-last-modified-at", "~> 1.0"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rubocop-jekyll", "~> 0.4"

spec/test_jekyll-last-modified-at.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "spec_helper"
-require "jekyll-last-modified-at"
 
 describe(Jekyll::JekyllSitemap) do
   let(:overrides) do
@@ -21,16 +20,31 @@
   let(:site)     { Jekyll::Site.new(config) }
   let(:contents) { File.read(dest_dir("sitemap.xml")) }
   before(:each) do
+    # simulate `last_modified_at` injection by `jekyll-last-modified-at` plugin
+    Jekyll::Hooks.register([:pages, :documents], :post_init) do |page|
+      page.data["last_modified_at"] = Time.parse("2015-01-18T00:00:00+00:00")
+    end
+
     site.process
   end
 
   context "with jekyll-last-modified-at" do
     it "correctly adds the modified time to the posts" do
-      expect(contents).to match  %r!<loc>http://example.org/2015/01/18/jekyll-last-modified-at.html</loc>\s+<lastmod>2015-01-19T07:03:38\+00:00</lastmod>!
+      expect(contents).to match(
+        %r!
+          <loc>http://example.org/2015/01/18/jekyll-last-modified-at.html</loc>\s+
+          <lastmod>2015-01-18T00:00:00\+00:00</lastmod>
+        !x
+      )
     end
 
     it "correctly adds the modified time to the pages" do
-      expect(contents).to match  %r!<loc>http://example.org/jekyll-last-modified-at/page.html</loc>\s+<lastmod>2015-01-19T07:03:38\+00:00</lastmod>!
+      expect(contents).to match(
+        %r!
+          <loc>http://example.org/jekyll-last-modified-at/page.html</loc>\s+
+          <lastmod>2015-01-18T00:00:00\+00:00</lastmod>
+        !x
+      )
     end
   end
 end