= assert_valid_asset plugin for Rails

assert_valid_asset is a plugin to validate your (X)HTML and CSS using the W3C Validator 
web service (http://validator.w3.org/) and the W3C CSS Validation Service 
(http://jigsaw.w3.org/css-validator) as part of your functional or unit tests. 
The css and html fragments are cached in $RAILS_ROOT/tmp/test/assets as are the results 
from the web service. This means that your tests will not be slowed down unless the output 
has changed.

The code started life as a few modifications to Scott Raymond's assert_valid_markup
(http://redgreenblu.com/svn/projects/assert_valid_markup/) and evolved to cache fragments
and results in $RAILS_ROOT/tmp/test/assets rather than the system temp directory. Then the 
ability to validate CSS files was added. I also added the ability to skip checks if the 
"NONET" environment variable is set to "true". 

A more recent version made it possible to display the content with the line numbers by
adding a line such as "self.display_invalid_content = true" into test_helper.rb in the
Test::Unit::TestCase class.

The ability to automatically validate content generated as a result of a action can be enabled
by adding the line "self.auto_validate = true" into test_helper.rb in the Test::Unit::TestCase
class. This will generate content according to the mime type of content. (x)html will be passed
to assert_valid_markup and css will be passed to assert_valid_css. You can also exclude
specific tests by putting them into an an auto_validate_excludes or instead can choose to only
include tests in list auto_validate_includes.

i.e. The following will automatically validate content generated in the test_foo and test_bar tests.

    class Test::Unit::TestCase
      self.auto_validate = true
    end

    class FooControllerTest < Test::Unit::TestCase

      self.auto_validate_excludes = [:test_baz]

      def test_foo; ... ; end
      def test_bar; ... ; end
      def test_baz; ... ; end
    end

i.e. The following will automatically validate content generated in the test_baz test.

    class Test::Unit::TestCase
      self.auto_validate = true
    end

    class FooControllerTest < Test::Unit::TestCase

      self.auto_validate_includes = [:test_baz]

      def test_foo; ... ; end
      def test_bar; ... ; end
      def test_baz; ... ; end
    end


== HowTo Validate (X)HTML

  # Calling the assertion with no parameters validates whatever is in @request.body,
  # which is automatically set by the existing get/post/etc helpers. For example:

    class FooControllerTest < Test::Unit::TestCase
      def test_bar_markup
        get :bar
        assert_valid_markup
      end
    end

  # Add a string parameter to the assertion to validate any random fragment. For example:

    class FooControllerTest < Test::Unit::TestCase
      def test_bar_markup
        assert_valid_markup "<div>Hello, world.</div>"
      end
    end

  # For the ultimate in convenience, use the class-level method to validate a slew of
  # actions in one line. Par exemple:

    class FooControllerTest < Test::Unit::TestCase
      assert_valid_markup :bar, :baz, :qux
    end

== HowTo Validate CSS

  # Pass a string parameter to the assertion to validate a css fragment. For example:

    class FooControllerTest < Test::Unit::TestCase
      def test_bar_css
        assert_valid_css(File.open("#{RAILS_ROOT}/public/stylesheets/bar.css",'rb').read)
      end
    end

  # For the ultimate in convenience, use the class-level method to validate a slew of
  # css files in one line. Assumes that the CSS files are relative to 
  # $RAILS_ROOT/public/stylesheets/ and end with '.css'. The following example validates 
  # $RAILS_ROOT/public/stylesheets/layout.css, $RAILS_ROOT/public/stylesheets/standard.css
  # and $RAILS_ROOT/public/stylesheets/theme.css

    class FooControllerTest < Test::Unit::TestCase
      assert_valid_css_files 'layout', 'standard', 'theme'
    end

== Details

License: Released under the MIT license.
Latest Version: http://www.realityforge.org/svn/public/code/assert-valid-asset/trunk/

== Credits

Scott Raymond <sco@scottraymond.net> for the initial version. 
Peter Donald <peter at realityforge dot org> to add validation of CSS files and fix caching.
Simon Stapleton for inspiration to add who added support display_invalid_content.
Clifford T. Matthews fix for ruby 1.8.5 and configuration of server endpoints.
Tomasz Wegrzanowski for replacing class variables with class_inheritable_accessor.
Cédric Deltheil for ensuring process_with_auto_validate returns the response.