From d3fc6d9b470d4d55217cdadd48b99d5d0ee264ad Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Wed, 21 Aug 2013 19:25:18 -0700
Subject: [PATCH 1/8] Filters Manage Dependencies

* Add dependency management test cases for each `Filter` with a
  dependency
* Add `assert_dependency_management_error` custom assertion which
  asserts a custom exception and message are raised if a dependency
  is missing
* Move all `Filter` dependencies to `Gemfile` `:test` block for
  test cases and CI
* Implement `TestingDependency` helper to abstract unloading and
  loading `Gemfile` `:test` block gems when asserting dependency
  management errors
* Implement `MissingDependencyException` custom exception with
 `MESSAGE` constant as a format string, so each `Filter` raises a
  uniform exception
* Add `begin..rescue..end` blocks around each `Filter` `require`
  statement to raise a `MissingDependencyException` when a gem can
  not be loaded
* Update README.md detailing new dependency management with listing
  of `Filter` gem dependencies
* Add gemspec post install message to inform users their apps must
  bundle `Filter` dependencies
---
 Gemfile                                       | 21 ++++-
 README.md                                     | 21 ++++-
 html-pipeline.gemspec                         | 18 ++--
 lib/html/pipeline.rb                          |  1 -
 lib/html/pipeline/autolink_filter.rb          |  7 +-
 lib/html/pipeline/email_reply_filter.rb       |  9 +-
 lib/html/pipeline/emoji_filter.rb             |  9 +-
 lib/html/pipeline/filter.rb                   | 17 ++++
 lib/html/pipeline/markdown_filter.rb          |  9 +-
 lib/html/pipeline/plain_text_input_filter.rb  |  9 +-
 lib/html/pipeline/sanitization_filter.rb      |  7 +-
 lib/html/pipeline/syntax_highlight_filter.rb  |  9 +-
 lib/html/pipeline/textile_filter.rb           |  9 +-
 test/helpers/testing_dependency.rb            | 92 +++++++++++++++++++
 test/html/pipeline/autolink_filter_test.rb    |  4 +
 test/html/pipeline/email_reply_filter_test.rb |  7 ++
 test/html/pipeline/emoji_filter_test.rb       | 14 ++-
 test/html/pipeline/markdown_filter_test.rb    | 14 ++-
 .../pipeline/plain_text_input_filter_test.rb  |  4 +
 .../html/pipeline/sanitization_filter_test.rb |  4 +
 .../pipeline/syntax_highlight_filter_test.rb  |  7 ++
 test/html/pipeline/textile_filter_test.rb     |  7 ++
 test/test_helper.rb                           | 29 ++++--
 23 files changed, 282 insertions(+), 46 deletions(-)
 create mode 100644 test/helpers/testing_dependency.rb
 create mode 100644 test/html/pipeline/email_reply_filter_test.rb
 create mode 100644 test/html/pipeline/syntax_highlight_filter_test.rb
 create mode 100644 test/html/pipeline/textile_filter_test.rb

diff --git a/Gemfile b/Gemfile
index 5b4d46d6..5b6a046f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,9 +1,24 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
 # Specify your gem's dependencies in html-pipeline.gemspec
 gemspec
 
 group :development do
-  gem 'bundler'
-  gem 'rake'
+  gem "bundler"
+  gem "rake"
+end
+
+group :test do
+  gem "rinku",            "~> 1.7",   :require => false
+  gem "gemoji",           "~> 1.0",   :require => false
+  gem "RedCloth",         "~> 4.2.9", :require => false
+  gem "escape_utils",     "~> 0.3",   :require => false
+  gem "github-linguist",  "~> 2.6.2", :require => false
+  gem "github-markdown",  "~> 0.5",   :require => false
+
+  if RUBY_VERSION < "1.9.2"
+    gem "sanitize", ">= 2", "< 2.0.4", :require => false
+  else
+    gem "sanitize", "~> 2.0",          :require => false
+  end
 end
diff --git a/README.md b/README.md
index 950b35db..dd651d5c 100644
--- a/README.md
+++ b/README.md
@@ -98,18 +98,29 @@ filter.call
 * `TextileFilter` - convert textile to html
 * `TableOfContentsFilter` - anchor headings with name attributes and generate Table of Contents html unordered list linking headings
 
-## Syntax highlighting
+## Dependencies
 
+Filter gem dependencies are not bundled; you must bundle the filter's gem
+dependencies. The below list details filters with dependencies. For example,
 `SyntaxHighlightFilter` uses [github-linguist](https://github.com/github/linguist)
-to detect and highlight languages. It isn't included as a dependency by default
-because it's a large dependency and
-[a hassle to build on heroku](https://github.com/jch/html-pipeline/issues/33).
-To use the filter, add the following to your Gemfile:
+to detect and highlight languages. To use the `SyntaxHighlightFilter`,
+add the following to your Gemfile:
 
 ```ruby
 gem 'github-linguist'
 ```
 
+* `AutolinkFilter` - `rinku`
+* `EmailReplyFilter` - `escape_utils`
+* `EmojiFilter` - `gemoji`
+* `MarkdownFilter` - `github-markdown`
+* `PlainTextInputFilter` - `escape_utils`
+* `SanitizationFilter` - `sanitize`
+* `SyntaxHighlightFilter` - `github-linguist`
+* `TextileFilter` - `RedCloth`
+
+_Note:_ See [Gemfile](https://github.com/jch/html-pipeline/blob/master/Gemfile) `:test` block for version requirements.
+
 ## Examples
 
 We define different pipelines for different parts of our app. Here are a few
diff --git a/html-pipeline.gemspec b/html-pipeline.gemspec
index 0fd38289..bf45e3c6 100644
--- a/html-pipeline.gemspec
+++ b/html-pipeline.gemspec
@@ -15,13 +15,17 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^test})
   gem.require_paths = ["lib"]
 
-  gem.add_dependency "gemoji",          "~> 1.0"
-  gem.add_dependency "nokogiri",        RUBY_VERSION < "1.9.2" ? [">= 1.4", "< 1.6"] : "~> 1.4"
-  gem.add_dependency "github-markdown", "~> 0.5"
-  gem.add_dependency "sanitize",        RUBY_VERSION < "1.9.2" ? [">= 2", "< 2.0.4"] : "~> 2.0"
-  gem.add_dependency "rinku",           "~> 1.7"
-  gem.add_dependency "escape_utils",    "~> 0.3"
+  gem.add_dependency "nokogiri", RUBY_VERSION < "1.9.2" ? [">= 1.4", "< 1.6"] : "~> 1.4"
 
   gem.add_development_dependency "activesupport", RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : ">= 2"
-  gem.add_development_dependency "github-linguist", "~> 2.6.2"
+
+  gem.post_install_message = <<msg
+----------------------------------------------
+Thank you for installing html-pipeline!
+Filter gem dependencies are no longer bundled.
+You must bundle Filter gem dependencies.
+See html-pipeline README.md for more details.
+https://github.com/jch/html-pipeline
+----------------------------------------------
+msg
 end
diff --git a/lib/html/pipeline.rb b/lib/html/pipeline.rb
index eb24cb3a..2e526d93 100644
--- a/lib/html/pipeline.rb
+++ b/lib/html/pipeline.rb
@@ -1,6 +1,5 @@
 require "nokogiri"
 require "active_support/xml_mini/nokogiri" # convert Documents to hashes
-require "escape_utils"
 
 module HTML
   # GitHub HTML processing filters and utilities. This module includes a small
diff --git a/lib/html/pipeline/autolink_filter.rb b/lib/html/pipeline/autolink_filter.rb
index b63ad9ed..e263b8b4 100644
--- a/lib/html/pipeline/autolink_filter.rb
+++ b/lib/html/pipeline/autolink_filter.rb
@@ -1,4 +1,9 @@
-require 'rinku'
+begin
+  require "rinku"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "rinku", e.backtrace
+end
 
 module HTML
   class Pipeline
diff --git a/lib/html/pipeline/email_reply_filter.rb b/lib/html/pipeline/email_reply_filter.rb
index a63a09a2..6f64f658 100644
--- a/lib/html/pipeline/email_reply_filter.rb
+++ b/lib/html/pipeline/email_reply_filter.rb
@@ -1,3 +1,10 @@
+begin
+  require "escape_utils"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "escape_utils", e.backtrace
+end
+
 module HTML
   class Pipeline
     # HTML Filter that converts email reply text into an HTML DocumentFragment.
@@ -53,4 +60,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/emoji_filter.rb b/lib/html/pipeline/emoji_filter.rb
index 87fb8828..c2336a86 100644
--- a/lib/html/pipeline/emoji_filter.rb
+++ b/lib/html/pipeline/emoji_filter.rb
@@ -1,4 +1,9 @@
-require 'emoji'
+begin
+  require "gemoji"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "gemoji", e.backtrace
+end
 
 module HTML
   class Pipeline
@@ -51,4 +56,4 @@ def asset_root
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/filter.rb b/lib/html/pipeline/filter.rb
index 0fe5a831..6edcb0df 100644
--- a/lib/html/pipeline/filter.rb
+++ b/lib/html/pipeline/filter.rb
@@ -27,6 +27,23 @@ class Pipeline
     # Each filter may define additional options and output values. See the class
     # docs for more info.
     class Filter
+      # Public: Custom Exception raised when a Filter dependency is not installed.
+      #
+      # Examples
+      #
+      #   begin
+      #     require "rinku"
+      #   rescue LoadError => e
+      #     missing = HTML::Pipeline::Filter::MissingDependencyException
+      #     raise missing, missing::MESSAGE % "rinku", e.backtrace
+      #   end
+      class MissingDependencyException < StandardError
+        # Public: Format String for MissingDependencyException message.
+        MESSAGE = "Missing html-pipeline dependency: " +
+                  "Please add `%s` to your Gemfile; " +
+                  "see html-pipeline Gemfile for version."
+      end
+
       class InvalidDocumentException < StandardError; end
 
       def initialize(doc, context = nil, result = nil)
diff --git a/lib/html/pipeline/markdown_filter.rb b/lib/html/pipeline/markdown_filter.rb
index 6c25494e..db61a7f0 100644
--- a/lib/html/pipeline/markdown_filter.rb
+++ b/lib/html/pipeline/markdown_filter.rb
@@ -1,4 +1,9 @@
-require 'github/markdown'
+begin
+  require "github/markdown"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "github-markdown", e.backtrace
+end
 
 module HTML
   class Pipeline
@@ -26,4 +31,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/plain_text_input_filter.rb b/lib/html/pipeline/plain_text_input_filter.rb
index 3e776a75..db0876ef 100644
--- a/lib/html/pipeline/plain_text_input_filter.rb
+++ b/lib/html/pipeline/plain_text_input_filter.rb
@@ -1,3 +1,10 @@
+begin
+  require "escape_utils"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "escape_utils", e.backtrace
+end
+
 module HTML
   class Pipeline
     # Simple filter for plain text input. HTML escapes the text input and wraps it
@@ -8,4 +15,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/sanitization_filter.rb b/lib/html/pipeline/sanitization_filter.rb
index b5d65cf7..6ee6dd59 100644
--- a/lib/html/pipeline/sanitization_filter.rb
+++ b/lib/html/pipeline/sanitization_filter.rb
@@ -1,4 +1,9 @@
-require 'sanitize'
+begin
+  require "sanitize"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "sanitize", e.backtrace
+end
 
 module HTML
   class Pipeline
diff --git a/lib/html/pipeline/syntax_highlight_filter.rb b/lib/html/pipeline/syntax_highlight_filter.rb
index 6660faff..98e1ccd2 100644
--- a/lib/html/pipeline/syntax_highlight_filter.rb
+++ b/lib/html/pipeline/syntax_highlight_filter.rb
@@ -1,7 +1,8 @@
 begin
-  require 'linguist'
-rescue LoadError
-  raise LoadError, "You need to install 'github-linguist' before using the SyntaxHighlightFilter. See README.md for details"
+  require "linguist"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "github-linguist", e.backtrace
 end
 
 module HTML
@@ -30,4 +31,4 @@ def highlight_with_timeout_handling(lexer, text)
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/textile_filter.rb b/lib/html/pipeline/textile_filter.rb
index 31619087..b3bcd16b 100644
--- a/lib/html/pipeline/textile_filter.rb
+++ b/lib/html/pipeline/textile_filter.rb
@@ -1,3 +1,10 @@
+begin
+  require "redcloth"
+rescue LoadError => e
+  missing = HTML::Pipeline::Filter::MissingDependencyException
+  raise missing, missing::MESSAGE % "RedCloth", e.backtrace
+end
+
 module HTML
   class Pipeline
     # HTML Filter that converts Textile text into HTML and converts into a
@@ -18,4 +25,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/test/helpers/testing_dependency.rb b/test/helpers/testing_dependency.rb
new file mode 100644
index 00000000..234de1e4
--- /dev/null
+++ b/test/helpers/testing_dependency.rb
@@ -0,0 +1,92 @@
+# Public: Methods useful for testing Filter dependencies. All methods are class
+# methods and should be called on the TestingDependency class.
+#
+# Examples
+#
+#   TestingDependency.temporarily_remove_dependency_by gem_name do
+#     exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
+#       load TestingDependency.filter_path_from filter_name
+#     end
+#   end
+class TestingDependency
+  # Public: Use to safely test a Filter's gem dependency error handling.
+  # For a certain gem dependency, remove the gem's loaded paths and features.
+  # Once these are removed, yield to a block which can assert a specific
+  # exception. Once the block is finished, add back the gem's paths and
+  # features to the load path and loaded features, so other tests can assert
+  # Filter functionality.
+  #
+  # gem_name - The String of the gem's name.
+  # block    - Required block which asserts gem dependency error handling.
+  #
+  # Examples
+  #
+  #   TestingDependency.temporarily_remove_dependency_by gem_name do
+  #     exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
+  #       load TestingDependency.filter_path_from filter_name
+  #     end
+  #   end
+  #
+  # Returns nothing.
+  def self.temporarily_remove_dependency_by(gem_name, &block)
+    paths = gem_load_paths_from gem_name
+    features = gem_loaded_features_from gem_name
+
+    $LOAD_PATH.delete_if { |path| paths.include? path }
+    $LOADED_FEATURES.delete_if { |feature| features.include? feature }
+
+    yield
+
+    $LOAD_PATH.unshift(*paths)
+    $LOADED_FEATURES.unshift(*features)
+  end
+
+  # Public: Find a Filter's load path.
+  #
+  # gem_name - The String of the gem's name.
+  #
+  # Examples
+  #
+  #   filter_path_from("autolink_filter")
+  #   # => "/Users/simeon/Projects/html-pipeline/test/helpers/../../lib/html/pipeline/autolink_filter.rb"
+  #
+  # Returns String of load path.
+  def self.filter_path_from(filter_name)
+    File.join(File.dirname(__FILE__), "..", "..", "lib", "html", "pipeline", "#{filter_name}.rb")
+  end
+
+  private
+  # Internal: Find a gem's load paths.
+  #
+  # gem_name - The String of the gem's name.
+  #
+  # Examples
+  #
+  #   gem_load_paths_from("rinku")
+  #   # => ["/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib"]
+  #
+  # Returns Array of load paths.
+  def self.gem_load_paths_from(gem_name)
+    $LOAD_PATH.select{ |path| /#{gem_name}/i =~ path }
+  end
+
+  # Internal: Find a gem's loaded features.
+  #
+  # gem_name - The String of the gem's name.
+  #
+  # Examples
+  #
+  #   gem_loaded_features_from("rinku")
+  #   # => ["/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib/rinku.bundle",
+  #        "/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib/rinku.rb"]
+  #
+  # Returns Array of loaded features.
+  def self.gem_loaded_features_from(gem_name)
+    # gem github-markdown has a feature "github/markdown.rb".
+    # Replace gem name dashes and underscores with regexp
+    # range to match all features.
+    gem_name_regexp = gem_name.split(/[-_]/).join("[\/_-]")
+
+    $LOADED_FEATURES.select{ |feature| /#{gem_name_regexp}/i =~ feature }
+  end
+end
diff --git a/test/html/pipeline/autolink_filter_test.rb b/test/html/pipeline/autolink_filter_test.rb
index dfda5e56..10c837fb 100644
--- a/test/html/pipeline/autolink_filter_test.rb
+++ b/test/html/pipeline/autolink_filter_test.rb
@@ -3,6 +3,10 @@
 AutolinkFilter = HTML::Pipeline::AutolinkFilter
 
 class HTML::Pipeline::AutolinkFilterTest < Test::Unit::TestCase
+  def test_dependency_management
+    assert_dependency_management_error "autolink_filter", "rinku"
+  end
+
   def test_uses_rinku_for_autolinking
     # just try to parse a complicated piece of HTML
     # that Rails auto_link cannot handle
diff --git a/test/html/pipeline/email_reply_filter_test.rb b/test/html/pipeline/email_reply_filter_test.rb
new file mode 100644
index 00000000..f6744e7e
--- /dev/null
+++ b/test/html/pipeline/email_reply_filter_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class HTML::Pipeline::EmailReplyFilterTest < Test::Unit::TestCase
+  def test_dependency_management
+    assert_dependency_management_error "email_reply_filter", "escape_utils"
+  end
+end
diff --git a/test/html/pipeline/emoji_filter_test.rb b/test/html/pipeline/emoji_filter_test.rb
index 20518484..2683bb98 100644
--- a/test/html/pipeline/emoji_filter_test.rb
+++ b/test/html/pipeline/emoji_filter_test.rb
@@ -1,12 +1,16 @@
-require 'test_helper'
+require "test_helper"
 
 class HTML::Pipeline::EmojiFilterTest < Test::Unit::TestCase
   EmojiFilter = HTML::Pipeline::EmojiFilter
-  
+
+  def test_dependency_management
+    assert_dependency_management_error "emoji_filter", "gemoji"
+  end
+
   def test_emojify
-    filter = EmojiFilter.new("<p>:shipit:</p>", {:asset_root => 'https://foo.com'})
+    filter = EmojiFilter.new("<p>:shipit:</p>", {:asset_root => "https://foo.com"})
     doc = filter.call
-    assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
+    assert_match "https://foo.com/emoji/shipit.png", doc.search("img").attr("src").value
   end
   
   def test_required_context_validation
@@ -15,4 +19,4 @@ def test_required_context_validation
     }
     assert_match /:asset_root/, exception.message
   end
-end
\ No newline at end of file
+end
diff --git a/test/html/pipeline/markdown_filter_test.rb b/test/html/pipeline/markdown_filter_test.rb
index a0b2f732..dfc2442e 100644
--- a/test/html/pipeline/markdown_filter_test.rb
+++ b/test/html/pipeline/markdown_filter_test.rb
@@ -18,6 +18,10 @@ def setup
       "```"
   end
 
+  def test_dependency_management
+    assert_dependency_management_error "markdown_filter", "github-markdown"
+  end
+
   def test_fails_when_given_a_documentfragment
     body = "<p>heyo</p>"
     doc  = HTML::Pipeline.parse(body)
@@ -27,26 +31,26 @@ def test_fails_when_given_a_documentfragment
   def test_gfm_enabled_by_default
     doc = MarkdownFilter.to_document(@haiku, {})
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 2, doc.search('br').size
+    assert_equal 2, doc.search("br").size
   end
 
   def test_disabling_gfm
     doc = MarkdownFilter.to_document(@haiku, :gfm => false)
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 0, doc.search('br').size
+    assert_equal 0, doc.search("br").size
   end
 
   def test_fenced_code_blocks
     doc = MarkdownFilter.to_document(@code)
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 1, doc.search('pre').size
+    assert_equal 1, doc.search("pre").size
   end
 
   def test_fenced_code_blocks_with_language
     doc = MarkdownFilter.to_document(@code.sub("```", "``` ruby"))
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 1, doc.search('pre').size
-    assert_equal 'ruby', doc.search('pre').first['lang']
+    assert_equal 1, doc.search("pre").size
+    assert_equal "ruby", doc.search("pre").first["lang"]
   end
 end
 
diff --git a/test/html/pipeline/plain_text_input_filter_test.rb b/test/html/pipeline/plain_text_input_filter_test.rb
index 22c419f4..8f2daddb 100644
--- a/test/html/pipeline/plain_text_input_filter_test.rb
+++ b/test/html/pipeline/plain_text_input_filter_test.rb
@@ -3,6 +3,10 @@
 class HTML::Pipeline::PlainTextInputFilterTest < Test::Unit::TestCase
   PlainTextInputFilter = HTML::Pipeline::PlainTextInputFilter
 
+  def test_dependency_management
+    assert_dependency_management_error "plain_text_input_filter", "escape_utils"
+  end
+
   def test_fails_when_given_a_documentfragment
     body = "<p>heyo</p>"
     doc  = Nokogiri::HTML::DocumentFragment.parse(body)
diff --git a/test/html/pipeline/sanitization_filter_test.rb b/test/html/pipeline/sanitization_filter_test.rb
index db9c98df..c271ff83 100644
--- a/test/html/pipeline/sanitization_filter_test.rb
+++ b/test/html/pipeline/sanitization_filter_test.rb
@@ -3,6 +3,10 @@
 class HTML::Pipeline::SanitizationFilterTest < Test::Unit::TestCase
   SanitizationFilter = HTML::Pipeline::SanitizationFilter
 
+  def test_dependency_management
+    assert_dependency_management_error "sanitization_filter", "sanitize"
+  end
+
   def test_removing_script_tags
     orig = %(<p><img src="http://github.com/img.png" /><script></script></p>)
     html = SanitizationFilter.call(orig).to_s
diff --git a/test/html/pipeline/syntax_highlight_filter_test.rb b/test/html/pipeline/syntax_highlight_filter_test.rb
new file mode 100644
index 00000000..426837e3
--- /dev/null
+++ b/test/html/pipeline/syntax_highlight_filter_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class HTML::Pipeline::SyntaxHighlightFilterTest < Test::Unit::TestCase
+  def test_dependency_management
+    assert_dependency_management_error "syntax_highlight_filter", "github-linguist"
+  end
+end
diff --git a/test/html/pipeline/textile_filter_test.rb b/test/html/pipeline/textile_filter_test.rb
new file mode 100644
index 00000000..4d0b802c
--- /dev/null
+++ b/test/html/pipeline/textile_filter_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class HTML::Pipeline::TextileFilterTest < Test::Unit::TestCase
+  def test_dependency_management
+    assert_dependency_management_error "textile_filter", "RedCloth"
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index bce1cb33..b999d4ad 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,14 +1,15 @@
-require 'bundler/setup'
-require 'html/pipeline'
-require 'test/unit'
+require "bundler/setup"
+require "html/pipeline"
+require "test/unit"
+require "helpers/testing_dependency"
 
-require 'active_support/core_ext/object/try'
+require "active_support/core_ext/object/try"
 
 module TestHelpers
   # Asserts that `needle` is not a member of `haystack`, where
   # `haystack` is any object that responds to `include?`.
   def assert_doesnt_include(needle, haystack, message = nil)
-    error = '<?> included in <?>'
+    error = "<?> included in <?>"
     message = build_message(message, error, needle.to_s, Array(haystack).map(&:to_s))
 
     assert_block message do
@@ -19,7 +20,7 @@ def assert_doesnt_include(needle, haystack, message = nil)
   # Asserts that `needle` is a member of `haystack`, where
   # `haystack` is any object that responds to `include?`.
   def assert_includes(needle, haystack, message = nil)
-    error = '<?> not included in <?>'
+    error = "<?> not included in <?>"
     message = build_message(message, error, needle.to_s, Array(haystack).map(&:to_s))
 
     assert_block message do
@@ -33,6 +34,20 @@ def assert_equal_html(expected, actual)
     assert_equal Nokogiri::HTML::DocumentFragment.parse(expected).to_hash,
                  Nokogiri::HTML::DocumentFragment.parse(actual).to_hash
   end
+
+  # Asserts that when a Filter is loaded without its dependencies installed,
+  # a HTML::Pipeline::Filter::MissingDependencyException is raised with a
+  # message describing the problem and a fix.
+  def assert_dependency_management_error(filter_name, gem_name)
+    TestingDependency.temporarily_remove_dependency_by gem_name do
+      exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
+        load TestingDependency.filter_path_from filter_name
+      end
+
+      assert_equal exception.message,
+        "Missing html-pipeline dependency: Please add `#{gem_name}` to your Gemfile; see html-pipeline Gemfile for version."
+    end
+  end
 end
 
-Test::Unit::TestCase.send(:include, TestHelpers)
\ No newline at end of file
+Test::Unit::TestCase.send(:include, TestHelpers)

From c25c89098045b3a5e6584b3f234123696d6a0b51 Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 27 Aug 2013 19:19:13 -0700
Subject: [PATCH 2/8] Address Pull Request comments: * Copy edit README.md * In
 gemspec, link README.md dependencies and update post install message * Rename
 test helper to `assert_dependency` * Remove `TestingDependency` in favor of
 stubbing `Kernal#require`

---
 README.md                                     |  2 +-
 html-pipeline.gemspec                         |  7 +-
 test/helpers/testing_dependency.rb            | 92 -------------------
 test/html/pipeline/autolink_filter_test.rb    |  2 +-
 test/html/pipeline/email_reply_filter_test.rb |  2 +-
 test/html/pipeline/emoji_filter_test.rb       |  2 +-
 test/html/pipeline/markdown_filter_test.rb    |  2 +-
 .../pipeline/plain_text_input_filter_test.rb  |  2 +-
 .../html/pipeline/sanitization_filter_test.rb |  2 +-
 .../pipeline/syntax_highlight_filter_test.rb  |  2 +-
 test/html/pipeline/textile_filter_test.rb     |  2 +-
 test/test_helper.rb                           | 17 ++--
 12 files changed, 22 insertions(+), 112 deletions(-)
 delete mode 100644 test/helpers/testing_dependency.rb

diff --git a/README.md b/README.md
index dd651d5c..169cbaa4 100644
--- a/README.md
+++ b/README.md
@@ -103,7 +103,7 @@ filter.call
 Filter gem dependencies are not bundled; you must bundle the filter's gem
 dependencies. The below list details filters with dependencies. For example,
 `SyntaxHighlightFilter` uses [github-linguist](https://github.com/github/linguist)
-to detect and highlight languages. To use the `SyntaxHighlightFilter`,
+to detect and highlight languages. For example, to use the `SyntaxHighlightFilter`,
 add the following to your Gemfile:
 
 ```ruby
diff --git a/html-pipeline.gemspec b/html-pipeline.gemspec
index bf45e3c6..23df17de 100644
--- a/html-pipeline.gemspec
+++ b/html-pipeline.gemspec
@@ -20,12 +20,11 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "activesupport", RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : ">= 2"
 
   gem.post_install_message = <<msg
-----------------------------------------------
+-------------------------------------------------
 Thank you for installing html-pipeline!
-Filter gem dependencies are no longer bundled.
 You must bundle Filter gem dependencies.
 See html-pipeline README.md for more details.
-https://github.com/jch/html-pipeline
-----------------------------------------------
+https://github.com/jch/html-pipeline#dependencies
+-------------------------------------------------
 msg
 end
diff --git a/test/helpers/testing_dependency.rb b/test/helpers/testing_dependency.rb
deleted file mode 100644
index 234de1e4..00000000
--- a/test/helpers/testing_dependency.rb
+++ /dev/null
@@ -1,92 +0,0 @@
-# Public: Methods useful for testing Filter dependencies. All methods are class
-# methods and should be called on the TestingDependency class.
-#
-# Examples
-#
-#   TestingDependency.temporarily_remove_dependency_by gem_name do
-#     exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
-#       load TestingDependency.filter_path_from filter_name
-#     end
-#   end
-class TestingDependency
-  # Public: Use to safely test a Filter's gem dependency error handling.
-  # For a certain gem dependency, remove the gem's loaded paths and features.
-  # Once these are removed, yield to a block which can assert a specific
-  # exception. Once the block is finished, add back the gem's paths and
-  # features to the load path and loaded features, so other tests can assert
-  # Filter functionality.
-  #
-  # gem_name - The String of the gem's name.
-  # block    - Required block which asserts gem dependency error handling.
-  #
-  # Examples
-  #
-  #   TestingDependency.temporarily_remove_dependency_by gem_name do
-  #     exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
-  #       load TestingDependency.filter_path_from filter_name
-  #     end
-  #   end
-  #
-  # Returns nothing.
-  def self.temporarily_remove_dependency_by(gem_name, &block)
-    paths = gem_load_paths_from gem_name
-    features = gem_loaded_features_from gem_name
-
-    $LOAD_PATH.delete_if { |path| paths.include? path }
-    $LOADED_FEATURES.delete_if { |feature| features.include? feature }
-
-    yield
-
-    $LOAD_PATH.unshift(*paths)
-    $LOADED_FEATURES.unshift(*features)
-  end
-
-  # Public: Find a Filter's load path.
-  #
-  # gem_name - The String of the gem's name.
-  #
-  # Examples
-  #
-  #   filter_path_from("autolink_filter")
-  #   # => "/Users/simeon/Projects/html-pipeline/test/helpers/../../lib/html/pipeline/autolink_filter.rb"
-  #
-  # Returns String of load path.
-  def self.filter_path_from(filter_name)
-    File.join(File.dirname(__FILE__), "..", "..", "lib", "html", "pipeline", "#{filter_name}.rb")
-  end
-
-  private
-  # Internal: Find a gem's load paths.
-  #
-  # gem_name - The String of the gem's name.
-  #
-  # Examples
-  #
-  #   gem_load_paths_from("rinku")
-  #   # => ["/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib"]
-  #
-  # Returns Array of load paths.
-  def self.gem_load_paths_from(gem_name)
-    $LOAD_PATH.select{ |path| /#{gem_name}/i =~ path }
-  end
-
-  # Internal: Find a gem's loaded features.
-  #
-  # gem_name - The String of the gem's name.
-  #
-  # Examples
-  #
-  #   gem_loaded_features_from("rinku")
-  #   # => ["/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib/rinku.bundle",
-  #        "/Users/simeon/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/rinku-1.7.3/lib/rinku.rb"]
-  #
-  # Returns Array of loaded features.
-  def self.gem_loaded_features_from(gem_name)
-    # gem github-markdown has a feature "github/markdown.rb".
-    # Replace gem name dashes and underscores with regexp
-    # range to match all features.
-    gem_name_regexp = gem_name.split(/[-_]/).join("[\/_-]")
-
-    $LOADED_FEATURES.select{ |feature| /#{gem_name_regexp}/i =~ feature }
-  end
-end
diff --git a/test/html/pipeline/autolink_filter_test.rb b/test/html/pipeline/autolink_filter_test.rb
index 10c837fb..50f301bc 100644
--- a/test/html/pipeline/autolink_filter_test.rb
+++ b/test/html/pipeline/autolink_filter_test.rb
@@ -4,7 +4,7 @@
 
 class HTML::Pipeline::AutolinkFilterTest < Test::Unit::TestCase
   def test_dependency_management
-    assert_dependency_management_error "autolink_filter", "rinku"
+    assert_dependency "autolink_filter", "rinku"
   end
 
   def test_uses_rinku_for_autolinking
diff --git a/test/html/pipeline/email_reply_filter_test.rb b/test/html/pipeline/email_reply_filter_test.rb
index f6744e7e..13a519fc 100644
--- a/test/html/pipeline/email_reply_filter_test.rb
+++ b/test/html/pipeline/email_reply_filter_test.rb
@@ -2,6 +2,6 @@
 
 class HTML::Pipeline::EmailReplyFilterTest < Test::Unit::TestCase
   def test_dependency_management
-    assert_dependency_management_error "email_reply_filter", "escape_utils"
+    assert_dependency "email_reply_filter", "escape_utils"
   end
 end
diff --git a/test/html/pipeline/emoji_filter_test.rb b/test/html/pipeline/emoji_filter_test.rb
index 2683bb98..ad3bbc4e 100644
--- a/test/html/pipeline/emoji_filter_test.rb
+++ b/test/html/pipeline/emoji_filter_test.rb
@@ -4,7 +4,7 @@ class HTML::Pipeline::EmojiFilterTest < Test::Unit::TestCase
   EmojiFilter = HTML::Pipeline::EmojiFilter
 
   def test_dependency_management
-    assert_dependency_management_error "emoji_filter", "gemoji"
+    assert_dependency "emoji_filter", "gemoji"
   end
 
   def test_emojify
diff --git a/test/html/pipeline/markdown_filter_test.rb b/test/html/pipeline/markdown_filter_test.rb
index dfc2442e..7161ea43 100644
--- a/test/html/pipeline/markdown_filter_test.rb
+++ b/test/html/pipeline/markdown_filter_test.rb
@@ -19,7 +19,7 @@ def setup
   end
 
   def test_dependency_management
-    assert_dependency_management_error "markdown_filter", "github-markdown"
+    assert_dependency "markdown_filter", "github-markdown"
   end
 
   def test_fails_when_given_a_documentfragment
diff --git a/test/html/pipeline/plain_text_input_filter_test.rb b/test/html/pipeline/plain_text_input_filter_test.rb
index 8f2daddb..a7f40903 100644
--- a/test/html/pipeline/plain_text_input_filter_test.rb
+++ b/test/html/pipeline/plain_text_input_filter_test.rb
@@ -4,7 +4,7 @@ class HTML::Pipeline::PlainTextInputFilterTest < Test::Unit::TestCase
   PlainTextInputFilter = HTML::Pipeline::PlainTextInputFilter
 
   def test_dependency_management
-    assert_dependency_management_error "plain_text_input_filter", "escape_utils"
+    assert_dependency "plain_text_input_filter", "escape_utils"
   end
 
   def test_fails_when_given_a_documentfragment
diff --git a/test/html/pipeline/sanitization_filter_test.rb b/test/html/pipeline/sanitization_filter_test.rb
index c271ff83..498e9c02 100644
--- a/test/html/pipeline/sanitization_filter_test.rb
+++ b/test/html/pipeline/sanitization_filter_test.rb
@@ -4,7 +4,7 @@ class HTML::Pipeline::SanitizationFilterTest < Test::Unit::TestCase
   SanitizationFilter = HTML::Pipeline::SanitizationFilter
 
   def test_dependency_management
-    assert_dependency_management_error "sanitization_filter", "sanitize"
+    assert_dependency "sanitization_filter", "sanitize"
   end
 
   def test_removing_script_tags
diff --git a/test/html/pipeline/syntax_highlight_filter_test.rb b/test/html/pipeline/syntax_highlight_filter_test.rb
index 426837e3..6c344789 100644
--- a/test/html/pipeline/syntax_highlight_filter_test.rb
+++ b/test/html/pipeline/syntax_highlight_filter_test.rb
@@ -2,6 +2,6 @@
 
 class HTML::Pipeline::SyntaxHighlightFilterTest < Test::Unit::TestCase
   def test_dependency_management
-    assert_dependency_management_error "syntax_highlight_filter", "github-linguist"
+    assert_dependency "syntax_highlight_filter", "github-linguist"
   end
 end
diff --git a/test/html/pipeline/textile_filter_test.rb b/test/html/pipeline/textile_filter_test.rb
index 4d0b802c..4bb511e2 100644
--- a/test/html/pipeline/textile_filter_test.rb
+++ b/test/html/pipeline/textile_filter_test.rb
@@ -2,6 +2,6 @@
 
 class HTML::Pipeline::TextileFilterTest < Test::Unit::TestCase
   def test_dependency_management
-    assert_dependency_management_error "textile_filter", "RedCloth"
+    assert_dependency "textile_filter", "RedCloth"
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index b999d4ad..5f63b798 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,7 +1,6 @@
 require "bundler/setup"
 require "html/pipeline"
 require "test/unit"
-require "helpers/testing_dependency"
 
 require "active_support/core_ext/object/try"
 
@@ -38,15 +37,19 @@ def assert_equal_html(expected, actual)
   # Asserts that when a Filter is loaded without its dependencies installed,
   # a HTML::Pipeline::Filter::MissingDependencyException is raised with a
   # message describing the problem and a fix.
-  def assert_dependency_management_error(filter_name, gem_name)
-    TestingDependency.temporarily_remove_dependency_by gem_name do
-      exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
-        load TestingDependency.filter_path_from filter_name
+  def assert_dependency(filter_name, gem_name)
+    Kernel.module_eval do
+      def require(name)
+        raise LoadError
       end
+    end
 
-      assert_equal exception.message,
-        "Missing html-pipeline dependency: Please add `#{gem_name}` to your Gemfile; see html-pipeline Gemfile for version."
+    exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
+      load File.join(File.dirname(__FILE__), "..", "lib", "html", "pipeline", "#{filter_name}.rb")
     end
+
+    assert_equal exception.message,
+      "Missing html-pipeline dependency: Please add `#{gem_name}` to your Gemfile; see html-pipeline Gemfile for version."
   end
 end
 

From f0983dca6d9afde4d6ec172bffdb406d55f0bb5b Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 27 Aug 2013 21:08:19 -0700
Subject: [PATCH 3/8] Textile Filter does require RedCloth

---
 bin/html-pipeline | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/bin/html-pipeline b/bin/html-pipeline
index eb4064ca..f1d8ed45 100755
--- a/bin/html-pipeline
+++ b/bin/html-pipeline
@@ -54,8 +54,6 @@ else
     case name
     when "Text"
       raise NameError # Text filter doesn't work, no call method
-    when "Textile"
-      require "RedCloth" # Textile filter doesn't require RedCloth
     end
 
     HTML::Pipeline.const_get("#{name}Filter")
@@ -77,4 +75,4 @@ context = {
   :gfm        => true
 }
 
-puts HTML::Pipeline.new(filters, context).call(ARGF.read)[:output]
\ No newline at end of file
+puts HTML::Pipeline.new(filters, context).call(ARGF.read)[:output]

From f9c6d0607ce50a4ad3b0afb4005cba0680a3356d Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 27 Aug 2013 21:19:04 -0700
Subject: [PATCH 4/8] Move ActiveSupport::XmlMini_Nokogiri to test helper,
 since its mixed in #to_hash is only used by #assert_equal_html

---
 lib/html/pipeline.rb | 1 -
 test/test_helper.rb  | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/html/pipeline.rb b/lib/html/pipeline.rb
index 2e526d93..7677af9a 100644
--- a/lib/html/pipeline.rb
+++ b/lib/html/pipeline.rb
@@ -1,5 +1,4 @@
 require "nokogiri"
-require "active_support/xml_mini/nokogiri" # convert Documents to hashes
 
 module HTML
   # GitHub HTML processing filters and utilities. This module includes a small
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 5f63b798..783e8e93 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -3,6 +3,7 @@
 require "test/unit"
 
 require "active_support/core_ext/object/try"
+require "active_support/xml_mini/nokogiri" # convert Documents to hashes
 
 module TestHelpers
   # Asserts that `needle` is not a member of `haystack`, where

From 0471de42da3f375af4d7d05a13e35e947e984dd2 Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 22 Oct 2013 19:36:08 -0700
Subject: [PATCH 5/8] Relative link to Gemfile

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index f8a72bba..20562b75 100644
--- a/README.md
+++ b/README.md
@@ -119,7 +119,7 @@ gem 'github-linguist'
 * `SyntaxHighlightFilter` - `github-linguist`
 * `TextileFilter` - `RedCloth`
 
-_Note:_ See [Gemfile](https://github.com/jch/html-pipeline/blob/master/Gemfile) `:test` block for version requirements.
+_Note:_ See [Gemfile](/Gemfile) `:test` block for version requirements.
 
 ## 3rd Party Extensions
 

From 154ef94444a648f5d74d5774a5786a7dafa1aae0 Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 22 Oct 2013 20:03:47 -0700
Subject: [PATCH 6/8] Don't test dependency management since its testing
 require and is brittle

---
 test/html/pipeline/autolink_filter_test.rb    |  4 ---
 test/html/pipeline/email_reply_filter_test.rb |  7 ----
 test/html/pipeline/emoji_filter_test.rb       | 14 +++-----
 test/html/pipeline/markdown_filter_test.rb    | 14 +++-----
 .../pipeline/plain_text_input_filter_test.rb  |  4 ---
 .../html/pipeline/sanitization_filter_test.rb |  4 ---
 .../pipeline/syntax_highlight_filter_test.rb  |  4 ---
 test/html/pipeline/textile_filter_test.rb     |  7 ----
 test/test_helper.rb                           | 32 ++++---------------
 9 files changed, 17 insertions(+), 73 deletions(-)
 delete mode 100644 test/html/pipeline/email_reply_filter_test.rb
 delete mode 100644 test/html/pipeline/textile_filter_test.rb

diff --git a/test/html/pipeline/autolink_filter_test.rb b/test/html/pipeline/autolink_filter_test.rb
index 5ff1e5b4..f8fe0c9d 100644
--- a/test/html/pipeline/autolink_filter_test.rb
+++ b/test/html/pipeline/autolink_filter_test.rb
@@ -3,10 +3,6 @@
 AutolinkFilter = HTML::Pipeline::AutolinkFilter
 
 class HTML::Pipeline::AutolinkFilterTest < Test::Unit::TestCase
-  def test_dependency_management
-    assert_dependency "autolink_filter", "rinku"
-  end
-
   def test_uses_rinku_for_autolinking
     # just try to parse a complicated piece of HTML
     # that Rails auto_link cannot handle
diff --git a/test/html/pipeline/email_reply_filter_test.rb b/test/html/pipeline/email_reply_filter_test.rb
deleted file mode 100644
index 13a519fc..00000000
--- a/test/html/pipeline/email_reply_filter_test.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require "test_helper"
-
-class HTML::Pipeline::EmailReplyFilterTest < Test::Unit::TestCase
-  def test_dependency_management
-    assert_dependency "email_reply_filter", "escape_utils"
-  end
-end
diff --git a/test/html/pipeline/emoji_filter_test.rb b/test/html/pipeline/emoji_filter_test.rb
index ad3bbc4e..20518484 100644
--- a/test/html/pipeline/emoji_filter_test.rb
+++ b/test/html/pipeline/emoji_filter_test.rb
@@ -1,16 +1,12 @@
-require "test_helper"
+require 'test_helper'
 
 class HTML::Pipeline::EmojiFilterTest < Test::Unit::TestCase
   EmojiFilter = HTML::Pipeline::EmojiFilter
-
-  def test_dependency_management
-    assert_dependency "emoji_filter", "gemoji"
-  end
-
+  
   def test_emojify
-    filter = EmojiFilter.new("<p>:shipit:</p>", {:asset_root => "https://foo.com"})
+    filter = EmojiFilter.new("<p>:shipit:</p>", {:asset_root => 'https://foo.com'})
     doc = filter.call
-    assert_match "https://foo.com/emoji/shipit.png", doc.search("img").attr("src").value
+    assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
   end
   
   def test_required_context_validation
@@ -19,4 +15,4 @@ def test_required_context_validation
     }
     assert_match /:asset_root/, exception.message
   end
-end
+end
\ No newline at end of file
diff --git a/test/html/pipeline/markdown_filter_test.rb b/test/html/pipeline/markdown_filter_test.rb
index 7161ea43..a0b2f732 100644
--- a/test/html/pipeline/markdown_filter_test.rb
+++ b/test/html/pipeline/markdown_filter_test.rb
@@ -18,10 +18,6 @@ def setup
       "```"
   end
 
-  def test_dependency_management
-    assert_dependency "markdown_filter", "github-markdown"
-  end
-
   def test_fails_when_given_a_documentfragment
     body = "<p>heyo</p>"
     doc  = HTML::Pipeline.parse(body)
@@ -31,26 +27,26 @@ def test_fails_when_given_a_documentfragment
   def test_gfm_enabled_by_default
     doc = MarkdownFilter.to_document(@haiku, {})
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 2, doc.search("br").size
+    assert_equal 2, doc.search('br').size
   end
 
   def test_disabling_gfm
     doc = MarkdownFilter.to_document(@haiku, :gfm => false)
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 0, doc.search("br").size
+    assert_equal 0, doc.search('br').size
   end
 
   def test_fenced_code_blocks
     doc = MarkdownFilter.to_document(@code)
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 1, doc.search("pre").size
+    assert_equal 1, doc.search('pre').size
   end
 
   def test_fenced_code_blocks_with_language
     doc = MarkdownFilter.to_document(@code.sub("```", "``` ruby"))
     assert doc.kind_of?(HTML::Pipeline::DocumentFragment)
-    assert_equal 1, doc.search("pre").size
-    assert_equal "ruby", doc.search("pre").first["lang"]
+    assert_equal 1, doc.search('pre').size
+    assert_equal 'ruby', doc.search('pre').first['lang']
   end
 end
 
diff --git a/test/html/pipeline/plain_text_input_filter_test.rb b/test/html/pipeline/plain_text_input_filter_test.rb
index a7f40903..22c419f4 100644
--- a/test/html/pipeline/plain_text_input_filter_test.rb
+++ b/test/html/pipeline/plain_text_input_filter_test.rb
@@ -3,10 +3,6 @@
 class HTML::Pipeline::PlainTextInputFilterTest < Test::Unit::TestCase
   PlainTextInputFilter = HTML::Pipeline::PlainTextInputFilter
 
-  def test_dependency_management
-    assert_dependency "plain_text_input_filter", "escape_utils"
-  end
-
   def test_fails_when_given_a_documentfragment
     body = "<p>heyo</p>"
     doc  = Nokogiri::HTML::DocumentFragment.parse(body)
diff --git a/test/html/pipeline/sanitization_filter_test.rb b/test/html/pipeline/sanitization_filter_test.rb
index 498e9c02..db9c98df 100644
--- a/test/html/pipeline/sanitization_filter_test.rb
+++ b/test/html/pipeline/sanitization_filter_test.rb
@@ -3,10 +3,6 @@
 class HTML::Pipeline::SanitizationFilterTest < Test::Unit::TestCase
   SanitizationFilter = HTML::Pipeline::SanitizationFilter
 
-  def test_dependency_management
-    assert_dependency "sanitization_filter", "sanitize"
-  end
-
   def test_removing_script_tags
     orig = %(<p><img src="http://github.com/img.png" /><script></script></p>)
     html = SanitizationFilter.call(orig).to_s
diff --git a/test/html/pipeline/syntax_highlight_filter_test.rb b/test/html/pipeline/syntax_highlight_filter_test.rb
index bd7b9be5..2dea999f 100644
--- a/test/html/pipeline/syntax_highlight_filter_test.rb
+++ b/test/html/pipeline/syntax_highlight_filter_test.rb
@@ -3,10 +3,6 @@
 SyntaxHighlightFilter = HTML::Pipeline::SyntaxHighlightFilter
 
 class HTML::Pipeline::SyntaxHighlightFilterTest < Test::Unit::TestCase
-  def test_dependency_management
-    assert_dependency "syntax_highlight_filter", "github-linguist"
-  end
-
   def test_highlight_default
     filter = SyntaxHighlightFilter.new \
       "<pre>hello</pre>", :highlight => "coffeescript"
diff --git a/test/html/pipeline/textile_filter_test.rb b/test/html/pipeline/textile_filter_test.rb
deleted file mode 100644
index 4bb511e2..00000000
--- a/test/html/pipeline/textile_filter_test.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require "test_helper"
-
-class HTML::Pipeline::TextileFilterTest < Test::Unit::TestCase
-  def test_dependency_management
-    assert_dependency "textile_filter", "RedCloth"
-  end
-end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index fc4b57b6..65e38906 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,15 +1,15 @@
-require "bundler/setup"
-require "html/pipeline"
-require "test/unit"
+require 'bundler/setup'
+require 'html/pipeline'
+require 'test/unit'
 
-require "active_support/core_ext/string"
-require "active_support/core_ext/object/try"
+require 'active_support/core_ext/string'
+require 'active_support/core_ext/object/try'
 
 module TestHelpers
   # Asserts that `needle` is not a member of `haystack`, where
   # `haystack` is any object that responds to `include?`.
   def assert_doesnt_include(needle, haystack, message = nil)
-    error = "<?> included in <?>"
+    error = '<?> included in <?>'
     message = build_message(message, error, needle.to_s, Array(haystack).map(&:to_s))
 
     assert_block message do
@@ -20,7 +20,7 @@ def assert_doesnt_include(needle, haystack, message = nil)
   # Asserts that `needle` is a member of `haystack`, where
   # `haystack` is any object that responds to `include?`.
   def assert_includes(needle, haystack, message = nil)
-    error = "<?> not included in <?>"
+    error = '<?> not included in <?>'
     message = build_message(message, error, needle.to_s, Array(haystack).map(&:to_s))
 
     assert_block message do
@@ -34,24 +34,6 @@ def assert_equal_html(expected, actual)
     assert_equal Nokogiri::HTML::DocumentFragment.parse(expected).to_hash,
                  Nokogiri::HTML::DocumentFragment.parse(actual).to_hash
   end
-
-  # Asserts that when a Filter is loaded without its dependencies installed,
-  # a HTML::Pipeline::Filter::MissingDependencyException is raised with a
-  # message describing the problem and a fix.
-  def assert_dependency(filter_name, gem_name)
-    Kernel.module_eval do
-      def require(name)
-        raise LoadError
-      end
-    end
-
-    exception = assert_raise HTML::Pipeline::Filter::MissingDependencyException do
-      load File.join(File.dirname(__FILE__), "..", "lib", "html", "pipeline", "#{filter_name}.rb")
-    end
-
-    assert_equal exception.message,
-      "Missing html-pipeline dependency: Please add `#{gem_name}` to your Gemfile; see html-pipeline Gemfile for version."
-  end
 end
 
 Test::Unit::TestCase.send(:include, TestHelpers)

From 6ff25ad54876996d052241e577e3aaf651d4265c Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 22 Oct 2013 20:04:23 -0700
Subject: [PATCH 7/8] No need for MissingDependencyException

---
 lib/html/pipeline/filter.rb | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/lib/html/pipeline/filter.rb b/lib/html/pipeline/filter.rb
index 6edcb0df..0fe5a831 100644
--- a/lib/html/pipeline/filter.rb
+++ b/lib/html/pipeline/filter.rb
@@ -27,23 +27,6 @@ class Pipeline
     # Each filter may define additional options and output values. See the class
     # docs for more info.
     class Filter
-      # Public: Custom Exception raised when a Filter dependency is not installed.
-      #
-      # Examples
-      #
-      #   begin
-      #     require "rinku"
-      #   rescue LoadError => e
-      #     missing = HTML::Pipeline::Filter::MissingDependencyException
-      #     raise missing, missing::MESSAGE % "rinku", e.backtrace
-      #   end
-      class MissingDependencyException < StandardError
-        # Public: Format String for MissingDependencyException message.
-        MESSAGE = "Missing html-pipeline dependency: " +
-                  "Please add `%s` to your Gemfile; " +
-                  "see html-pipeline Gemfile for version."
-      end
-
       class InvalidDocumentException < StandardError; end
 
       def initialize(doc, context = nil, result = nil)

From a0acb6956fdede396b814ce695eef78af0d56b96 Mon Sep 17 00:00:00 2001
From: "Simeon F. Willbanks" <sfw@simeonfosterwillbanks.com>
Date: Tue, 22 Oct 2013 20:11:41 -0700
Subject: [PATCH 8/8] If a dependency is missing, exit with a 1 status and
 write help message to STDERR.

---
 lib/html/pipeline/autolink_filter.rb         | 5 ++---
 lib/html/pipeline/email_reply_filter.rb      | 5 ++---
 lib/html/pipeline/emoji_filter.rb            | 5 ++---
 lib/html/pipeline/markdown_filter.rb         | 5 ++---
 lib/html/pipeline/plain_text_input_filter.rb | 5 ++---
 lib/html/pipeline/sanitization_filter.rb     | 5 ++---
 lib/html/pipeline/syntax_highlight_filter.rb | 5 ++---
 lib/html/pipeline/textile_filter.rb          | 5 ++---
 8 files changed, 16 insertions(+), 24 deletions(-)

diff --git a/lib/html/pipeline/autolink_filter.rb b/lib/html/pipeline/autolink_filter.rb
index b6428585..4a2f6f73 100644
--- a/lib/html/pipeline/autolink_filter.rb
+++ b/lib/html/pipeline/autolink_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "rinku"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "rinku", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'rinku' for AutolinkFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/email_reply_filter.rb b/lib/html/pipeline/email_reply_filter.rb
index 6f64f658..cb8261a8 100644
--- a/lib/html/pipeline/email_reply_filter.rb
+++ b/lib/html/pipeline/email_reply_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "escape_utils"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "escape_utils", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'escape_utils' for EmailReplyFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/emoji_filter.rb b/lib/html/pipeline/emoji_filter.rb
index c2336a86..b061cf5d 100644
--- a/lib/html/pipeline/emoji_filter.rb
+++ b/lib/html/pipeline/emoji_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "gemoji"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "gemoji", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'gemoji' for EmojiFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/markdown_filter.rb b/lib/html/pipeline/markdown_filter.rb
index db61a7f0..d08e5412 100644
--- a/lib/html/pipeline/markdown_filter.rb
+++ b/lib/html/pipeline/markdown_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "github/markdown"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "github-markdown", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'github-markdown' for MarkdownFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/plain_text_input_filter.rb b/lib/html/pipeline/plain_text_input_filter.rb
index db0876ef..c6e468d7 100644
--- a/lib/html/pipeline/plain_text_input_filter.rb
+++ b/lib/html/pipeline/plain_text_input_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "escape_utils"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "escape_utils", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'escape_utils' for PlainTextInputFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/sanitization_filter.rb b/lib/html/pipeline/sanitization_filter.rb
index 6ee6dd59..33877bc6 100644
--- a/lib/html/pipeline/sanitization_filter.rb
+++ b/lib/html/pipeline/sanitization_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "sanitize"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "sanitize", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'sanitize' for SanitizationFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/syntax_highlight_filter.rb b/lib/html/pipeline/syntax_highlight_filter.rb
index b136f17e..ccdd31e0 100644
--- a/lib/html/pipeline/syntax_highlight_filter.rb
+++ b/lib/html/pipeline/syntax_highlight_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "linguist"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "github-linguist", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'github-linguist' for SyntaxHighlightFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/textile_filter.rb b/lib/html/pipeline/textile_filter.rb
index b3bcd16b..d08bce33 100644
--- a/lib/html/pipeline/textile_filter.rb
+++ b/lib/html/pipeline/textile_filter.rb
@@ -1,8 +1,7 @@
 begin
   require "redcloth"
-rescue LoadError => e
-  missing = HTML::Pipeline::Filter::MissingDependencyException
-  raise missing, missing::MESSAGE % "RedCloth", e.backtrace
+rescue LoadError => _
+  abort "Missing dependency 'RedCloth' for TextileFilter. See README.md for details."
 end
 
 module HTML