diff --git a/.gitignore b/.gitignore
index 0112337..a1f4633 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,5 +3,5 @@
 Gemfile.lock
 dev_notes.md
 .vscode
+spec/fixtures/unit/.jekyll-cache
 pkg
-spec/fixtures/unit/.jekyll-cache
\ No newline at end of file
diff --git a/.rubocop.yml b/.rubocop.yml
index 6190cf1..bd51008 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -2,7 +2,7 @@ inherit_gem:
   jekyll: .rubocop.yml
 
 AllCops:
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.6
   Exclude:
     - vendor/**/*
 
diff --git a/.travis.yml b/.travis.yml
index 45dd139..ea5038b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,7 @@ language: ruby
 rvm:
 - 2.5
 - 2.4
-- 2.3
+- 2.6
 before_install:
 - gem update --system
 - gem install bundler
diff --git a/Gemfile b/Gemfile
index be173b2..7f4f5e9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
-source "https://rubygems.org"
+source 'https://rubygems.org'
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 92557b5..2e9b334 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/gem_tasks"
-require "rspec/core/rake_task"
+require 'bundler/gem_tasks'
+require 'rspec/core/rake_task'
 
 RSpec::Core::RakeTask.new(:spec)
diff --git a/jekyll-target-blank.gemspec b/jekyll-target-blank.gemspec
index 2dc5c3b..03d3ed4 100644
--- a/jekyll-target-blank.gemspec
+++ b/jekyll-target-blank.gemspec
@@ -1,27 +1,27 @@
 # frozen_string_literal: true
 
-lib = File.expand_path("lib", __dir__)
+lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require "jekyll-target-blank/version"
+require 'jekyll-target-blank/version'
 
 Gem::Specification.new do |spec|
-  spec.name = "jekyll-target-blank"
+  spec.name = 'jekyll-target-blank'
   spec.version = JekyllTargetBlank::VERSION
-  spec.authors = ["Keith Mifsud"]
-  spec.email = ["mifsud.k@gmail.com"]
-  spec.summary = "Target Blank automatically changes the external links to open in a new browser."
-  spec.description = "Target Blank automatically changes the external links to open in a new browser for Jekyll sites."
-  spec.homepage = "https://github.com/keithmifsud/jekyll-target-blank"
-  spec.license = "MIT"
+  spec.authors = ['Keith Mifsud']
+  spec.email = ['mifsud.k@gmail.com']
+  spec.summary = 'Target Blank automatically changes the external links to open in a new browser.'
+  spec.description = 'Target Blank automatically changes the external links to open in a new browser for Jekyll sites.'
+  spec.homepage = 'https://github.com/keithmifsud/jekyll-target-blank'
+  spec.license = 'MIT'
   spec.files = `git ls-files -z`.split("\x0")
-  spec.require_paths = ["lib"]
-  spec.required_ruby_version = ">= 2.3.0"
+  spec.require_paths = ['lib']
+  spec.required_ruby_version = '>= 2.3.0'
+  spec.add_dependency 'jekyll', '>= 3.0', '<5.0'
+  spec.add_dependency 'nokogiri', '~> 1.10'
+  spec.add_development_dependency 'bundler', '~> 2.0'
+  spec.add_development_dependency 'rake', '~> 12.0'
+  spec.add_development_dependency 'rspec', '~> 3.0'
+  spec.add_development_dependency 'rubocop', '>= 0.68.0', '<= 0.72.0'
+  spec.add_development_dependency "rubocop-jekyll", "~> 0.10.0"
 
-  spec.add_dependency "jekyll", "~> 3.0"
-  spec.add_dependency "nokogiri", "~> 1.10.4"
-
-  spec.add_development_dependency "bundler", "~> 2.0"
-  spec.add_development_dependency "rake", "~> 12.0"
-  spec.add_development_dependency "rspec", "~> 3.0"
-  spec.add_development_dependency "rubocop", "0.55"
 end
diff --git a/lib/jekyll-target-blank.rb b/lib/jekyll-target-blank.rb
index 75a68be..88ce8d4 100644
--- a/lib/jekyll-target-blank.rb
+++ b/lib/jekyll-target-blank.rb
@@ -7,7 +7,7 @@
 module Jekyll
   class TargetBlank
     BODY_START_TAG         = "<body"
-    OPENING_BODY_TAG_REGEX = %r!<body([^<>]*)>\s*!
+    OPENING_BODY_TAG_REGEX = %r!<body([^<>]*)>\s*!.freeze
 
     class << self
       # Public: Processes the content and updated the external links
@@ -117,13 +117,9 @@ def configure_adding_additional_css_classes
 
       # Private: Handles the default rel attribute values
       def add_default_rel_attributes?
-        if should_not_include_noopener?
-          @should_add_noopener = false
-        end
+        @should_add_noopener = false if should_not_include_noopener?
 
-        if should_not_include_noreferrer?
-          @should_add_noreferrrer = false
-        end
+        @should_add_noreferrrer = false if should_not_include_noreferrer?
       end
 
       # Private: Sets any extra rel attribute values
@@ -142,7 +138,7 @@ def add_css_classes_if_required(link)
         if @should_add_css_classes
           existing_classes = get_existing_css_classes(link)
           existing_classes = " " + existing_classes unless existing_classes.to_s.empty?
-          link["class"]    = @css_classes_to_add + existing_classes
+          link["class"] = @css_classes_to_add + existing_classes
         end
       end
 
@@ -158,27 +154,30 @@ def add_target_blank_attribute(link)
       # link = Nokogiri node.
       def add_rel_attributes(link)
         rel = ""
-        if @should_add_noopener
-          rel = "noopener"
-        end
+        rel = add_noopener_to_rel(rel)
 
         if @should_add_noreferrrer
-          unless rel.empty?
-            rel += " "
-          end
+          rel += " " unless rel.empty?
           rel += "noreferrer"
         end
 
         if @should_add_extra_rel_attribute_values
-          unless rel.empty?
-            rel += " "
-          end
+          rel += " " unless rel.empty?
           rel += @extra_rel_attribute_values
         end
 
-        unless rel.empty?
-          link["rel"] = rel
+        link["rel"] = rel unless rel.empty?
+      end
+
+      # Private: Adds noopener attribute.
+      #
+      # rel = string
+      def add_noopener_to_rel(rel)
+        if @should_add_noopener
+          rel += " " unless rel.empty?
+          rel += "noopener"
         end
+        rel
       end
 
       # Private: Checks if the link is a mailto url.
@@ -193,7 +192,7 @@ def not_mailto_link?(link)
       #
       # link - a url.
       def external?(link)
-        if link =~ URI.regexp(%w(http https))
+        if link&.match?(URI.regexp(%w(http https)))
           URI.parse(link).host != URI.parse(@site_url).host
         end
       end
@@ -332,6 +331,6 @@ def class_config
 end
 
 # Hooks into Jekyll's post_render event.
-Jekyll::Hooks.register %i[pages documents], :post_render do |doc|
+Jekyll::Hooks.register [:pages, :documents], :post_render do |doc|
   Jekyll::TargetBlank.process(doc) if Jekyll::TargetBlank.document_processable?(doc)
 end
diff --git a/lib/jekyll-target-blank/version.rb b/lib/jekyll-target-blank/version.rb
index 7407b3f..f137b4a 100644
--- a/lib/jekyll-target-blank/version.rb
+++ b/lib/jekyll-target-blank/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module JekyllTargetBlank
-  VERSION = "1.2.0"
+  VERSION = "2.0.0"
 end
diff --git a/spec/jekyll-target_spec.rb b/spec/jekyll-target_spec.rb
index 30906f8..06987e0 100644
--- a/spec/jekyll-target_spec.rb
+++ b/spec/jekyll-target_spec.rb
@@ -6,53 +6,51 @@
   let(:config_overrides) { {} }
   let(:config_overrides) do
     {
-      "url"         => "https://keith-mifsud.me",
-      "collections" => { "docs" => { "output" => "true" } },
+      'url' => 'https://keith-mifsud.me',
+      'collections' => { 'docs' => { 'output' => 'true' } }
     }
   end
   let(:configs) do
     Jekyll.configuration(config_overrides.merge(
-      {
-        "skip_config_files" => false,
-        "collections"       => { "docs" => { "output" => true } },
-        "source"            => unit_fixtures_dir,
-        "destination"       => unit_fixtures_dir("_site"),
-      }
-    ))
+                           'skip_config_files' => false,
+                           'collections' => { 'docs' => { 'output' => true } },
+                           'source' => unit_fixtures_dir,
+                           'destination' => unit_fixtures_dir('_site')
+                         ))
   end
   let(:target_blank) { described_class }
   let(:site) { Jekyll::Site.new(configs) }
   let(:posts) { site.posts.docs.sort.reverse }
 
   # get some fixtures
-  let(:post_with_external_markdown_link) { find_by_title(posts, "Post with external markdown link") }
+  let(:post_with_external_markdown_link) { find_by_title(posts, 'Post with external markdown link') }
 
-  let(:post_with_multiple_external_markdown_links) { find_by_title(posts, "Post with multiple external markdown links") }
+  let(:post_with_multiple_external_markdown_links) { find_by_title(posts, 'Post with multiple external markdown links') }
 
-  let(:post_with_relative_markdown_link) { find_by_title(posts, "Post with relative markdown link") }
+  let(:post_with_relative_markdown_link) { find_by_title(posts, 'Post with relative markdown link') }
 
-  let(:post_with_absolute_internal_markdown_link) { find_by_title(posts, "Post with absolute internal markdown link") }
+  let(:post_with_absolute_internal_markdown_link) { find_by_title(posts, 'Post with absolute internal markdown link') }
 
-  let(:post_with_html_anchor_tag) { find_by_title(posts, "Post with html anchor tag") }
+  let(:post_with_html_anchor_tag) { find_by_title(posts, 'Post with html anchor tag') }
 
-  let(:post_with_plain_text_link) { find_by_title(posts, "Post with plain text link") }
+  let(:post_with_plain_text_link) { find_by_title(posts, 'Post with plain text link') }
 
-  let(:document_with_a_processable_link) { find_by_title(site.collections["docs"].docs, "Document with a processable link") }
+  let(:document_with_a_processable_link) { find_by_title(site.collections['docs'].docs, 'Document with a processable link') }
 
-  let(:text_file) { find_by_title(site.collections["docs"].docs, "Text file") }
+  let(:text_file) { find_by_title(site.collections['docs'].docs, 'Text file') }
 
-  let(:post_with_code_block) { find_by_title(posts, "Post with code block") }
-  let(:document_with_liquid_tag) { find_by_title(site.collections["docs"].docs, "Document with liquid tag") }
+  let(:post_with_code_block) { find_by_title(posts, 'Post with code block') }
+  let(:document_with_liquid_tag) { find_by_title(site.collections['docs'].docs, 'Document with liquid tag') }
 
-  let(:document_with_include) { find_by_title(site.collections["docs"].docs, "Document with include") }
+  let(:document_with_include) { find_by_title(site.collections['docs'].docs, 'Document with include') }
 
-  let(:post_with_mailto_link) { find_by_title(posts, "Post with mailto link") }
+  let(:post_with_mailto_link) { find_by_title(posts, 'Post with mailto link') }
 
-  let(:post_with_external_html_link_and_random_css_classes) { find_by_title(posts, "Post with external html link and random css classes") }
+  let(:post_with_external_html_link_and_random_css_classes) { find_by_title(posts, 'Post with external html link and random css classes') }
 
-  let(:post_with_html_link_containing_the_specified_css_class) { find_by_title(posts, "Post with html link containing the specified css class") }
+  let(:post_with_html_link_containing_the_specified_css_class) { find_by_title(posts, 'Post with html link containing the specified css class') }
 
-  let(:post_with_external_link_containing_the_specified_css_class_and_other_css_classes) { find_by_title(posts, "Post with external link containing the specified css class and other css classes") }
+  let(:post_with_external_link_containing_the_specified_css_class_and_other_css_classes) { find_by_title(posts, 'Post with external link containing the specified css class and other css classes') }
 
   # define common wrappers.
   def para(content)
@@ -66,50 +64,50 @@ def para(content)
     site.render
   end
 
-  context "Without entries in config file" do
+  context 'Without entries in config file' do
     let(:config_overrides) do
-      { "target-blank" => { "add_css_classes" => false } }
+      { 'target-blank' => { 'add_css_classes' => false } }
     end
 
-    it "should add target attribute to external markdown link" do
+    it 'should add target attribute to external markdown link' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.'))
     end
 
-    it "should add target attribute to multiple external markdown links" do
+    it 'should add target attribute to multiple external markdown links' do
       expect(post_with_multiple_external_markdown_links.output).to include('<p>This post contains three links. The first link is to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>, the second link is, well, to <a href="https://keithmifsud.github.io" target="_blank" rel="noopener noreferrer">my website</a> and since <a href="https://github.com" target="_blank" rel="noopener noreferrer">GitHub</a> is so awesome, why not link to them too?</p>')
     end
 
-    it "should not add target attribute to relative markdown link" do
+    it 'should not add target attribute to relative markdown link' do
       expect(post_with_relative_markdown_link.output).to include(para('Link to <a href="/contact">contact page</a>.'))
 
       expect(post_with_relative_markdown_link.output).to_not include(para('Link to <a href="/contact" target="_blank" rel="noopener noreferrer">contact page</a>'))
     end
 
-    it "should not add target attribute to absolute internal link" do
+    it 'should not add target attribute to absolute internal link' do
       expect(post_with_absolute_internal_markdown_link.output).to include('<p>This is an absolute internal <a href="https://keith-mifsud.me/contact">link</a>.</p>')
     end
 
-    it "should correctly handle existing html anchor tag" do
+    it 'should correctly handle existing html anchor tag' do
       expect(post_with_html_anchor_tag.output).to include('<p>This is an <a href="https://google.com" target="_blank" rel="noopener noreferrer">anchor tag</a>.</p>')
     end
 
-    it "should not interfere with plain text link" do
-      expect(post_with_plain_text_link.output).to include("<p>This is a plain text link to https://google.com.</p>")
+    it 'should not interfere with plain text link' do
+      expect(post_with_plain_text_link.output).to include('<p>This is a plain text link to https://google.com.</p>')
     end
 
-    it "should process external links in collections" do
+    it 'should process external links in collections' do
       expect(document_with_a_processable_link.output).to include('<p>This is a valid <a href="https://google.com" target="_blank" rel="noopener noreferrer">link</a>.</p>')
     end
 
-    it "should process external links in pages" do
+    it 'should process external links in pages' do
       expect(site.pages.first.output).to include('<p>This is a valid <a href="https://google.com" target="_blank" rel="noopener noreferrer">link</a>.</p>')
     end
 
-    it "should not process links in non html files" do
-      expect(text_file.output).to eq("Valid [link](https://google.com).")
+    it 'should not process links in non html files' do
+      expect(text_file.output).to eq('Valid [link](https://google.com).')
     end
 
-    it "should not process link in code block but process link outside of block" do
+    it 'should not process link in code block but process link outside of block' do
       expect(post_with_code_block.output).to include('<span class="s1">\'https://google.com\'</span>')
 
       expect(post_with_code_block.output).not_to include('<span class="s1"><a href="https://google.com" target="_blank" rel="noopener noreferrer">https://google.com</a></span>')
@@ -117,307 +115,307 @@ def para(content)
       expect(post_with_code_block.output).to include('<p>Valid <a href="https://google.com" target="_blank" rel="noopener noreferrer">link</a></p>')
     end
 
-    it "should not break layouts" do
+    it 'should not break layouts' do
       expect(site.pages.first.output).to include('<html lang="en-US">')
       expect(site.pages.first.output).to include('<body class="wrap">')
     end
 
-    it "should not interfere with liquid tags" do
+    it 'should not interfere with liquid tags' do
       expect(document_with_liquid_tag.output).to include('<p>This <a href="/docs/document-with-liquid-tag.html">_docs/document-with-liquid-tag.md</a> is a document with a liquid tag.</p>')
     end
 
-    it "should not interfere with includes" do
-      expect(document_with_include.output).to include("<p>This is a document with an include: This is an include.</p>")
+    it 'should not interfere with includes' do
+      expect(document_with_include.output).to include('<p>This is a document with an include: This is an include.</p>')
     end
 
-    it "should not break layout content" do
-      expect(site.pages.first.output).to include("<div>Layout content started.</div>")
+    it 'should not break layout content' do
+      expect(site.pages.first.output).to include('<div>Layout content started.</div>')
 
-      expect(site.pages.first.output).to include("<div>Layout content ended.</div>")
+      expect(site.pages.first.output).to include('<div>Layout content ended.</div>')
     end
 
-    it "should not duplicate post content" do
+    it 'should not duplicate post content' do
       expect(post_with_external_markdown_link.output).to eq(post_with_layout_result)
     end
 
-    it "should ignore mailto links" do
+    it 'should ignore mailto links' do
       expect(post_with_mailto_link.output).to include(para('This is a <a href="mailto:mifsud.k@gmail.com?Subject=Just%20an%20email">mailto link</a>.'))
     end
   end
 
-  context "With a specified css class name" do
-    let(:target_blank_css_class) { "ext-link" }
+  context 'With a specified css class name' do
+    let(:target_blank_css_class) { 'ext-link' }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "css_class"       => target_blank_css_class,
-          "add_css_classes" => false,
-        },
+        'target-blank' => {
+          'css_class' => target_blank_css_class,
+          'add_css_classes' => false
+        }
       }
     end
 
-    it "should not add target attribute to external markdown link that does not have the specified css class" do
+    it 'should not add target attribute to external markdown link that does not have the specified css class' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank">Google</a>.'))
     end
 
-    it "should not add target attribute to external markdown link that does not have the specified css class even if it does have other css classes" do
+    it 'should not add target attribute to external markdown link that does not have the specified css class even if it does have other css classes' do
       expect(post_with_external_html_link_and_random_css_classes.output).to include(para('<a href="https://google.com" class="random-class another-random-class">Link</a>.'))
 
       expect(post_with_external_html_link_and_random_css_classes.output).to_not include('target="_blank" rel="noopener noreferrer"')
     end
 
-    it "should add target attribute to an external link containing the specified css class" do
+    it 'should add target attribute to an external link containing the specified css class' do
       expect(post_with_html_link_containing_the_specified_css_class.output).to include(para('<a href="https://google.com" class="ext-link" target="_blank" rel="noopener noreferrer">Link with the css class specified in config</a>.'))
     end
 
-    it "should add target attribute to an external link containing the specified css class even when other css classes are specified" do
+    it 'should add target attribute to an external link containing the specified css class even when other css classes are specified' do
       expect(post_with_external_link_containing_the_specified_css_class_and_other_css_classes.output).to include(para('This is <a href="https://not-keith-mifsud.me" class="random-class ext-link another-random-class" target="_blank" rel="noopener noreferrer">a link containing the specified css class and two other random css classes</a>.'))
     end
   end
 
-  context "Adds a CSS classes to the links" do
-    let(:target_blank_add_css_class) { "some-class" }
+  context 'Adds a CSS classes to the links' do
+    let(:target_blank_add_css_class) { 'some-class' }
     let(:config_overrides) do
-      { "target-blank" => { "add_css_classes" => target_blank_add_css_class } }
+      { 'target-blank' => { 'add_css_classes' => target_blank_add_css_class } }
     end
 
-    it "should add the CSS class specified in config" do
+    it 'should add the CSS class specified in config' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer" class="some-class">Google</a>.'))
     end
 
-    it "should add the CSS class specified in config even when the link already has a CSS class specified" do
+    it 'should add the CSS class specified in config even when the link already has a CSS class specified' do
       expect(post_with_html_link_containing_the_specified_css_class.output).to include(para('<a href="https://google.com" class="some-class ext-link" target="_blank" rel="noopener noreferrer">Link with the css class specified in config</a>.'))
     end
 
-    it "should add the CSS class specified in config even when the link has more than CSS classes already included" do
+    it 'should add the CSS class specified in config even when the link has more than CSS classes already included' do
       expect(post_with_external_link_containing_the_specified_css_class_and_other_css_classes.output).to include(para('This is <a href="https://not-keith-mifsud.me" class="some-class random-class ext-link another-random-class" target="_blank" rel="noopener noreferrer">a link containing the specified css class and two other random css classes</a>.'))
     end
   end
 
-  context "When more than one CSS classes are specified in config" do
-    it "should add the CSS classes specified in config" do
+  context 'When more than one CSS classes are specified in config' do
+    it 'should add the CSS classes specified in config' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer" class="some-class other-some-class another-some-class">Google</a>.'))
     end
 
-    it "should add the CSS classes specified in config even when the link already has a CSS class included" do
+    it 'should add the CSS classes specified in config even when the link already has a CSS class included' do
       expect(post_with_html_link_containing_the_specified_css_class.output).to include(para('<a href="https://google.com" class="some-class other-some-class another-some-class ext-link" target="_blank" rel="noopener noreferrer">Link with the css class specified in config</a>.'))
     end
 
-    it "should add the CSS classes specified in config even when the link already has more than one CSS classes included" do
+    it 'should add the CSS classes specified in config even when the link already has more than one CSS classes included' do
       expect(post_with_external_link_containing_the_specified_css_class_and_other_css_classes.output).to include(para('This is <a href="https://not-keith-mifsud.me" class="some-class other-some-class another-some-class random-class ext-link another-random-class" target="_blank" rel="noopener noreferrer">a link containing the specified css class and two other random css classes</a>.'))
     end
   end
 
-  context "When noopener is set to false in config" do
+  context 'When noopener is set to false in config' do
     let(:noopener) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener
+        }
       }
     end
 
-    it "should not add noopener value to the rel attribute" do
+    it 'should not add noopener value to the rel attribute' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.'))
     end
 
-    it "should still add noreferrer value to the rel attribute" do
+    it 'should still add noreferrer value to the rel attribute' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer">Google</a>.'))
     end
   end
 
-  context "When noreferrer is set to false in config" do
+  context 'When noreferrer is set to false in config' do
     let(:noreferrer) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noreferrer"      => noreferrer,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noreferrer' => noreferrer
+        }
       }
     end
 
-    it "should not add noreferrer value to the rel attribute" do
+    it 'should not add noreferrer value to the rel attribute' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.'))
     end
 
-    it "should still add noopener value to the rel attribute" do
+    it 'should still add noopener value to the rel attribute' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener">Google</a>.'))
     end
   end
 
-  context "When both noopener and noreferrer values are set to false in config" do
+  context 'When both noopener and noreferrer values are set to false in config' do
     let(:noopener) { false }
     let(:noreferrer) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "noreferrer"      => noreferrer,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'noreferrer' => noreferrer
+        }
       }
     end
 
-    it "should not include the rel attribute values" do
+    it 'should not include the rel attribute values' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.'))
     end
 
-    it "should not include the rel attribute noopener value" do
+    it 'should not include the rel attribute noopener value' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer">Google</a>.'))
     end
 
-    it "should not include the rel attribute noreferrer value" do
+    it 'should not include the rel attribute noreferrer value' do
       expect(post_with_external_markdown_link.output).to_not include(para('Link to <a href="https://google.com" target="_blank" rel="noopener">Google</a>.'))
     end
 
-    it "should not include any rel attributes" do
+    it 'should not include any rel attributes' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank">Google</a>.'))
     end
   end
 
-  context "When one additional rel attribute is added in config" do
-    let(:rel_attribute) { "nofollow" }
+  context 'When one additional rel attribute is added in config' do
+    let(:rel_attribute) { 'nofollow' }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should add the extra rel attribute together with the default ones" do
+    it 'should add the extra rel attribute together with the default ones' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer nofollow">Google</a>.'))
     end
   end
 
-  context "When more than one additional rel attributes are added in config" do
-    let(:rel_attribute) { "nofollow tag" }
+  context 'When more than one additional rel attributes are added in config' do
+    let(:rel_attribute) { 'nofollow tag' }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should add the extra rel attributes together with the default ones" do
+    it 'should add the extra rel attributes together with the default ones' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer nofollow tag">Google</a>.'))
     end
   end
 
-  context "When one extra rel attribute value are set in config and noopener is set to false" do
-    let(:rel_attribute) { "nofollow" }
+  context 'When one extra rel attribute value are set in config and noopener is set to false' do
+    let(:rel_attribute) { 'nofollow' }
     let(:noopener) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should the extra rel attribute value and not add the default noopener value" do
+    it 'should the extra rel attribute value and not add the default noopener value' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer nofollow">Google</a>.'))
     end
   end
 
-  context "When more than one extra rel attribute values are set in config and noopener is set to false" do
-    let(:rel_attribute) { "nofollow tag" }
+  context 'When more than one extra rel attribute values are set in config and noopener is set to false' do
+    let(:rel_attribute) { 'nofollow tag' }
     let(:noopener) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should the extra rel attribute values and not add the default noopener value" do
+    it 'should the extra rel attribute values and not add the default noopener value' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer nofollow tag">Google</a>.'))
     end
   end
 
-  context "When one extra rel attributes is set in config and both noopener and noreferer are set to false" do
-    let(:rel_attribute) { "nofollow" }
+  context 'When one extra rel attributes is set in config and both noopener and noreferer are set to false' do
+    let(:rel_attribute) { 'nofollow' }
     let(:noopener) { false }
     let(:noreferrer) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "noreferrer"      => noreferrer,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'noreferrer' => noreferrer,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should add the extra rel attribute value and no default ones" do
+    it 'should add the extra rel attribute value and no default ones' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="nofollow">Google</a>.'))
     end
   end
 
-  context "When more than one extra rel attribute values are set in config and both noopener and noreferer are set to false" do
-    let(:rel_attribute) { "nofollow tag" }
+  context 'When more than one extra rel attribute values are set in config and both noopener and noreferer are set to false' do
+    let(:rel_attribute) { 'nofollow tag' }
     let(:noopener) { false }
     let(:noreferrer) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "noreferrer"      => noreferrer,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'noreferrer' => noreferrer,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should add the extra rel attribute values and no default ones" do
+    it 'should add the extra rel attribute values and no default ones' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="nofollow tag">Google</a>.'))
     end
   end
 
-  context "When noopener is set to false in config but added to the rel config property" do
-    let(:rel_attribute) { "noopener" }
+  context 'When noopener is set to false in config but added to the rel config property' do
+    let(:rel_attribute) { 'noopener' }
     let(:noopener) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should still include the noopener rel attribute value" do
+    it 'should still include the noopener rel attribute value' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer noopener">Google</a>.'))
     end
   end
 
-  context "When noopener is set to false in config but added t0 the rel config property alongside one more extra rel attribute value." do
-    let(:rel_attribute) { "noopener nofollow" }
+  context 'When noopener is set to false in config but added t0 the rel config property alongside one more extra rel attribute value.' do
+    let(:rel_attribute) { 'noopener nofollow' }
     let(:noopener) { false }
     let(:config_overrides) do
       {
-        "target-blank" => {
-          "add_css_classes" => false,
-          "noopener"        => noopener,
-          "rel"             => rel_attribute,
-        },
+        'target-blank' => {
+          'add_css_classes' => false,
+          'noopener' => noopener,
+          'rel' => rel_attribute
+        }
       }
     end
 
-    it "should still include the noopener rel attribute value along the extra one" do
+    it 'should still include the noopener rel attribute value along the extra one' do
       expect(post_with_external_markdown_link.output).to include(para('Link to <a href="https://google.com" target="_blank" rel="noreferrer noopener nofollow">Google</a>.'))
     end
   end
@@ -425,22 +423,22 @@ def para(content)
   private
 
   def post_with_layout_result
-    <<-RESULT
-<!DOCTYPE HTML>
-<html lang="en-US">
-<head>
-    <meta charset="UTF-8">
-    <title>Post with external markdown link</title>
-    <meta name="viewport" content="width=device-width,initial-scale=1">
-    <link rel="stylesheet" href="/css/screen.css">
-</head>
-<body class="wrap">
-    <div>Layout content started.</div>
-<p>Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.</p>
-
-    <div>Layout content ended.</div>
-</body>
-</html>
+    <<~RESULT
+      <!DOCTYPE HTML>
+      <html lang="en-US">
+      <head>
+          <meta charset="UTF-8">
+          <title>Post with external markdown link</title>
+          <meta name="viewport" content="width=device-width,initial-scale=1">
+          <link rel="stylesheet" href="/css/screen.css">
+      </head>
+      <body class="wrap">
+          <div>Layout content started.</div>
+      <p>Link to <a href="https://google.com" target="_blank" rel="noopener noreferrer">Google</a>.</p>
+
+          <div>Layout content ended.</div>
+      </body>
+      </html>
     RESULT
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 8bb8103..94438e0 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
-require File.expand_path("../lib/jekyll-target-blank.rb", __dir__)
+require File.expand_path('../lib/jekyll-target-blank.rb', __dir__)
 
 RSpec.configure do |config|
-  UNIT_FIXTURES_DIR = File.expand_path("fixtures/unit", __dir__)
+  UNIT_FIXTURES_DIR = File.expand_path('fixtures/unit', __dir__)
 
-  INTEGRATION_FIXTURES_DIR = File.expand_path("fixtures/integration", __dir__)
+  INTEGRATION_FIXTURES_DIR = File.expand_path('fixtures/integration', __dir__)
 
   def unit_fixtures_dir(*paths)
     File.join(UNIT_FIXTURES_DIR, *paths)
@@ -16,7 +16,7 @@ def integration_fixtures_dir(*paths)
   end
 
   def find_by_title(docs, title)
-    docs.find { |d| d.data["title"] == title }
+    docs.find { |d| d.data['title'] == title }
   end
 
   # rspec-expectations config goes here. You can use an alternate