The trouble w/ fixtures

I don’t use fixtures in my specs. At all. The fundamental issue with fixtures is that they setup a state for your database as a whole (or at least the tables you loaded). So when you use fixtures all your specs are running against essentially the same state. As you build your application and things get more complex your fixtures become more complex and your state grows and grows. The needs of your specs, however, should pretty much stay the same. So when you go back and track down an issue causing some spec to blow up you have to deal with that spec running in a state that’s way beyond it’s needs.

Brittle specs

For example, lets stay I’m writing a spec to ensure that book.authors.living does not return any deceased authors. The state that I need to spec this is very simple: 1 Book with 1 living Author and 1 dead Author. Then I just need to make sure that when I run book.authors.living I don’t get the dead Author back. It might look something like this:

describe Book do
  describe "with authors" do
    fixtures :books, :authors
 
    it "should only find living authors" do
      Book.find_by_title("Foo's Diary").authors.living.should == [Author.find_by_name('Jim')]
    end
  end
end

Assuming I know that Jim is alive this would be a good spec. The problem is as I write specs I’m going to add more and more authors and this spec will quickly blow up. It’s not blowing up because the .living method broke though, it’s just blowing up because it’s no longer running in the state it expected.

Kill your fixtures

Without fixtures I would do something like:

describe Book do
  describe "with authors" do
    before :each do
       @book = Book.create! :title => "Foo's Diary"
       @book.authors << (@jim = Author.new(:name => 'Jim', :dead => false))
       @book.authors << (@jeff = Author.new(:name => 'Jeff', :dead => true))
    end
 
    it "should only find living authors" do
      @book.reload.authors.living.should == [@jim]
    end
  end
end

Now my spec will always run in the state I gave it. So the things I setup for my other specs won’t come back and blow this spec up. Furthermore, the state isn’t buried in multiple fixture files. It’s defined plainly right above the spec(s) which use it.

Simplify your life even more

Once you ditch your fixtures you’ll find a new love for writing specs. There’s a couple handy tools to simplify your life further though:

Factories

Dan Manges blogged about using factories to simplify creation of classes and to provide defaults. Since then there’s been a few plugins developed for quick and easy factories. We’ve been using Scott Taylor’s Fixture Replacement.

add!

add is similar to the << method of has_many associations except it sacrifices chainability in order to return the concatenated object. add! goes a step further and throws an exception if the concatenation failed. This is useful in specs because the exception (probably due to a validation error) will occur in your state setup and you will see the error message in your output when you run your specs. So the reason your spec just blew up is displayed for you.

With Fixture Replacement and add! the example above would look something like:

describe Book do
  describe "with authors" do
    before :each do
       @book = create_book :title => "Foo's Diary"
       @jim = @book.authors.add! new_author(:name => 'Jim')
       @jeff = @book.authors.add! new_author(:name => 'Jeff', :dead => true)
    end
 
    it "should only find living authors" do
      @book.reload.authors.living.should == [@jim]
    end
  end
end

Here’s a little chunk of code I’ve been using recently. It gives you .add
and .add! methods on your has_many relationships that work similar to the << method. The difference is that .add sacrifices chain-ability in order to return the object being added to the collection.

Adding instead of concatenating

Using book.authors << Author.new(:name => ‘Geoff’) returns true or false forcing you to do something like book.authors << (geoff = Author.new(:name => ‘Geoff’)) to maintain a reference to the new object. Using .add you can do geoff = book.authors.add Author.new(:name => 'Geoff')

No really…add!ing

Perhaps even more helpful (especially in specs) is the add! method. add! acts just like add except it raises a RecordInvalid exception on failure. So you can do geoff = book.authors.add! Author.new(:name => 'Geoff') and have your execution (or your transaction) halt if Geoff messed up and wasn’t valid.

Blowing up your specs

This comes in handy a lot in your specs as exceptions will be displayed as the reason for failure. So if you were to add a validation to your Author class that caused all the Author’s you were adding to Book’s all over your specs to be invalid, you would see it (along with your validation’s helpful error message) when you ran your specs.

The goods

Just drop this in a file in your /lib folder and require it in an initializer.

module ActiveRecord
  module Associations
    class AssociationCollection < AssociationProxy #:nodoc:
      # works just like << except returns the added records instead of self, so
      # it's not chainable but allows you to do something like:
      #   @jim = Book.authors.add Author.new(:name => 'jim')
      # (often saving a whole line of code!)
      def add(*records)
        self.<<(*records)
        unarray_if_lonely(records)
      end
 
      # works just like add except raises an exception on error
      def add!(*records)
        raise RecordInvalid.new(*records) unless self.<<(*records)
        unarray_if_lonely(records)
      end
 
      # if the given object is an array of size 1 then it returns the only
      # element itself (w/ no array), otherwise it just gives back object
      def unarray_if_lonely(object)
        (object.is_a?(Array) && object.length == 1) ? object.first : object
      end
    end
  end
end

Some people use scaffolds, some people don’t. To those who do and happen to have their project taking advantage of Haml, probably understand the pain it is to go through all those lame rhtml files and convert them to Haml. Thus, a quick and dirty solution has arrived. Meet your master: “RSpec Haml Scaffolds”.

It’s hosted at github over here:
http://github.com/dfischer/rspec-haml-scaffold-generator

To install the git way (until Rails’ script/install supports git) do this in your rails_root/vendor/plugins directory:

git clone git://github.com/dfischer/rspec-haml-scaffold-generator.git

Bam, you’re done. You should have a rspec-haml-scaffold folder in your vendor/plugins directory and when you fire up the following command:

script/generate

You should see “rspec_haml_scaffold” in the “installed generators…plugins” section.

Remember this is a quick and dirty version of the plugin. There may be a couple quirks with it, if so feel free to fork the repository on github and submit a patch!

p.s If anyone needs a github invite I have three left. All you need to do is request one in the comments, be sure to leave a way to contact you.