Re: Ruby unit testing

Jan Svitok wrote:
> Hi,
> 
> This is how I'd do it. I don't know the details, so your actual code
> will be different. This code was not run at all, so probably there are
> many typos/errors.
> You'd certainly choose another names than I've chosen.
> 
> First of all, if you want to test, it's good to split the code in
> small chunks so that each does a little bit of work. Thus you can test
> them separately. I tend to put the code inside some class as well...
> you know, the OOP ;-)
> 
> While adding tests, you want to change the code as little as possible,
> to not broke it. When you have the tests in place, you can safely
> change stuff (=refactor).
> 
> The final code could be a bit different from what is written in the
> mail, as the code was written before the text, and I was too lazy to
> fix it ;-)
> 
> Now the steps to the code below:
> 
> 1. minor corrections:
>   - at the end of the code 'end' is missing
>   - change |records| to |result| as you are iterating over Result(s)
>   - change each to collect as you seem to collect results (but I may be 
> wrong)
> 
> 2. move the whole each/collect block inside Result class as:
>    class Result < ...
>       def self.get_records
>          Result.find(:all).each do |result|
>             ...
>          end
>       end
>    end
> (you can omit the Result. before find)
> We have a function that returns something for all Results
> 
> what remains at the bottom is
>    records = Result.get_records
> 
> 3. The block doesn't return anything meaningful so:
>    - add just after class Result < ...:
> BuildStatus = Struct.new(:module_name, :build_status_since,
> :last_failure, :last_success, :build_number)
>   - add BuildStatus.new(module_name, build_status_since, last_failure,
> last_success, build_number) at the end of the block (inside it)
> 
> 4. Now we can add the first unit test at the very bottom:
> comment out the records = ... line
> and add:
> 
> if __FILE__ == $0
>    require 'test/unit'
> 
>    class TestResult < Test::Unit::TestCase
>       def test_get_records
>           assert_equal [], Result.get_records
>       end
>    end
> end
> 
> This test will fail if there are any results, but we have SOMETHING now.
> 
> 5. Let's make the test succeed:
> change the inside of the test:
> 
>       def test_get_records
>           results = Result.find(:all)
>           records =Result.get_records
>           assert_equal results.size, records.size
>           records.each do |record|
>              assert_equal Result::BuildStatus, record.class
>           end
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thanks for the long post Jan, youve given me a good insight into the way 
that my code should be tested. I think that its hard to see how it works 
exactly when you look at tests being done on other peoples code but when 
its your own, it makes a bit more sense.

I was dreading the idea that Id have refactor it. Not something i've 
done before as im very new to ruby code at the moment. In my original 
post i actually omitted a lot of the code which might have been vital to 
the way that you refactored it and now im a bit lost.

Heres the full code (only another few lines extra):

require 'net/http'
require 'uri'
require 'rexml/document'
require 'rubygems'
require_gem 'activerecord'


include REXML
def fetch(uri_str, limit=10)
  fail 'http redirect too deep' if limit.zero?
  puts "Scraping: #{uri_str}"
  response = Net::HTTP.get_response(URI.parse(uri_str))
  case response
  when Net::HTTPSuccess
    response
  when NetHTTPRedirection
    fetch(response['location'], limit-1)
  else
    response.error!
  end
end

#Connect to the database
ActiveRecord::Base.establish_connection(
  :adapter  => "mysql",
  :username => "root",
  :host     => "localhost",
  :password => "",
  :database => "build"
)

puts "connected to build database"


class Result < ActiveRecord::Base
end

records = Result.find(:all).each do |records|
  response = fetch(records.build_url)


  scraped_data = response.body

  table_start_pos = scraped_data.index('<table class="index" 
width="100%">')
  table_end_pos = scraped_data.index('</table>') + 9
  height = table_end_pos - table_start_pos

  #pick out the table
  gathered_data = response.body[table_start_pos,height]

  #convert Data to REXML
  converted_data = REXML::Document.new gathered_data
  module_name = XPath.first(converted_data, "//td[@class='data']/a/]")
  module_name = module_name

  build_status_since = XPath.first(converted_data, "//td[2]/em")
  build_status_since = build_status_since.text
  build_status_since = build_status_since.slice(/(\d+):(\d+)/)

  last_failure = XPath.first(converted_data, "//tbody/tr/td[3]")
  last_failure = last_failure.text

  last_success = XPath.first(converted_data, "//tbody/tr/td[4]")
  last_success = last_success.text

  build_number = XPath.first(converted_data, "//tbody/tr/td[5]")
  build_number = build_number.text



  #modify current entry for the build.

  Result.find(:all,:conditions => ["build_url = ?", 
records.build_url]).each do |b|
    b.build_status_since = build_status_since
    b.last_failure = last_failure
    b.last_success = last_success
    b.build_number = build_number
    b.save
    puts '#{module_name} successfully scraped.'
  end
end

I think I can nail the testing now but might need a hand with 
refactoring it. It was silly of me to leave that out of the original 
post, apologies.




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