Module: ReadPageCache

Defined in:
lib/read_page_cache.rb

Overview

Synopsis

The purpose of the module is to cache web pages used for testing by overriding the classes’ read_page method and replacing it with one that will cache pages.

Usage

Your main code needs to have a read_page(page) instance method(s). Here’s an example:

class ClassName
  def read_page(page)
    open(page).read
  end
end

Then your test code should include:

# default directory is '/tmp'
directory = '/path/to/cache/files'
require 'cache_extensions'
ReadPageCache.attach_to ClassName, directory

You may attach_to however many classes that you need to.

If you want to override all the read_page(page) methods in your application, then your test code can instead use:

# default directory is '/tmp'
directory = '/path/to/cache/files'
require 'cache_extensions'
ReadPageCache.attach_to_classes directory

That’s it. The first time you run your tests, the pages your application accesses with read_page will be cached, then the cached files will be used by all subsequent accesses.

Class Method Summary collapse

Class Method Details

.attach_to(cls, directory = '/tmp') ⇒ Object

Synopsis

Attach the read_page and cache_file methods to the given class (cls) and use the given directory for the cache files



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# File 'lib/read_page_cache.rb', line 44

def self.attach_to(cls, directory='/tmp')

  # define the read_page(page) method on the given class: cls
  cls.send('define_method', "read_page") do |page|
    data = nil
    filespec = page.gsub(/^http:\//, directory).gsub(/\/$/, '.html')
    if File.exist?(filespec)
      data = open(filespec).read
    else
      data = open(page).read
      _cache_file(page, data)
    end
    data
  end

  # define the cache_file(page, data) method on the given class: cls
  cls.send('define_method', "_cache_file") do |page, data|
    begin
      filespec = page.gsub(/^http:\//, directory).gsub(/\/$/, '.html')
      unless File.exist?(filespec)
        puts "caching #{filespec}"
        File.mkdirs(File.dirname(filespec))
        File.open(filespec, 'w') { |f| f.puts data }
      end
    rescue Exception => eMsg
      puts eMsg.to_s
    end
  end
end

.attach_to_classes(directory = '/tmp') ⇒ Object

Synopsis

Find all classes that have a read_page instance method and then overwrite that read_page method with one that handles the caching. Use the given directory for the cache files.



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# File 'lib/read_page_cache.rb', line 78

def self.attach_to_classes(directory='/tmp')
  ObjectSpace.each_object(Class) do |cls|
    # need to check all scopes for read_page instance method
    if(cls.public_instance_methods(false).include?("read_page") ||
      cls.protected_instance_methods(false).include?("read_page") ||
      cls.private_instance_methods(false).include?("read_page"))
      ReadPageCache.attach_to(cls, directory)
    end
  end
end