Dem Bones

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I happened to come across Jamie van Dyke's Building a Gem Using BDD article today. It seems the gods of my chain are telling me something and I must listen...

You can probably safely ignore this article, Jamie's write up is far superior...

First up, I install bones:

cstrom@jaynestown:~/repos$ gem install bones
--------------------------
 Keep rattlin' dem bones!
--------------------------
Successfully installed bones-2.5.1
1 gem installed

Then I create my gem template:

cstrom@jaynestown:~/repos$ bones create couch_design_docs
Created 'couch_design_docs'
Now you need to fix these files
(in /home/cstrom/repos/couch_design_docs)
README.txt:
  * [  2] [FIXME] (your name)
  * [  3] [FIXME] (url)
  * [  7] [FIXME] (describe your package)
  * [ 11] [FIXME] (list of features or problems)
  * [ 15] [FIXME] (code sample of usage)
  * [ 19] [FIXME] (list of requirements)
  * [ 23] [FIXME] (sudo gem install, anything else)
  * [ 29] [FIXME] (different license?)

Rakefile:
  * [ 22] [FIXME] (who is writing this software)'
  * [ 23] [FIXME] (your e-mail)'
  * [ 24] [FIXME] (project homepage)'

After fixing as many of those FIXMEs as possible, I move onto implementation. First up is directory parsing. In order to directory parse, the CouchDesignDocs::Directory object is going to need a valid directory. After creating a fixture directory, I begin driving development with spec/couch_design_docs_spec.rb:

require File.join(File.dirname(__FILE__), %w[spec_helper])

describe Directory do
  it "should require a root directory for instantiation" do
    lambda { Directory.new }.
      should raise_error

    lambda { Directory.new("foo") }.
      should raise_error

    lambda { Directory.new("fixtures")}.
      should_not raise_error
  end
end

Note: I added include CouchDesignDocs to spec/spec_helper.rb so that I could access Directory without the CouchDesignDocs:: namespace.

I implement that code with:

module CouchDesignDocs
  class Directory
    attr_accessor :couch_view_dir
    def initialize(path)
      Dir.new(path) # Just checkin'
      @couch_view_dir = path
    end
  end
end

The Dir.new call is made only to raise an exception for invalid paths. It is a quick, cheap way to get the code to behave as desired. Next I create a "valid directory" context and drive the file path expansion needed to build the CouchDB design document JSON structure:

  context "a valid directory" do
    before(:each) do
      @it = Directory.new("fixtures")
    end
    it "should list dirs, basename and contents of a file" do
      @it.expand_file("fixtures/a/b/c.js").
        should == ['a', 'b', 'c', "function(doc) { return true; }\n"]
    end
  end

After creating the fixtures/a/b/ directory and populating it with a very simple javascript function, I make the example pass with this code:

    def expand_file(filename)
      File.dirname(filename).
        gsub(/#{couch_view_dir}\/?/, '').
        split(/\//) +
      [
       File.basename(filename, '.js'),
       File.new(filename).read
      ]
    end

That will do for a stopping point tonight, I will continue with dem bones gem development tomorrow.