Speeding Up Factory_girl Tests With "Model.first Or"

Lately at work I’ve been trying to make sure that I follow test driven development. That means that I’m using rspec with factory_girl in order to make building objects to test against easier. As the amount of tests that I have grows, testing gets longer and longer.$

While this gives me a nice break from working, similar to the compile time that a large program used to give me at my old job, usually I want to see the results of my bugfix faster. Turning on rspec test timing had me confused though, because it was saying that the longest test was similar to this one:

describe Product do

  it "should have a working factory" do
    x = Factory(:product)
    x.should be_valid
    x2 = Factory(:product)
    x2.should be_valid

There’s nothing there - it’s all calls to factories that I’ve built. So I went investigating what was actually happening there by making a simple helper for telling me what was actually being built:

def get_model_classes
  [].tap do |r| 
    Dir["# {Rails.root.join("app/models/*.rb")}"].each do |fname|
      modelname = fname.split('/')[-1].split('.')[0].camelcase
      r << Kernel.const_get(modelname)

# shows a count of all of the relevant objects, to 
# determine when we are making too many objects in the world.
def show_object_counts(title = "")
  @@all_models ||= get_model_classes
  print "Objects in existence: # {title}\n"
  @@all_models.each do |k|
    if k.respond_to?(:all) then
      c = k.all.count
      next if c == 0
      print " - # {c} # {k}\n"

Adding a call after the model factory showed me that I was making 7 User, 5 Address, and about 21 other support objects in order to simply build a valid Product. There should be ways to eliminate a large number of those. A lot of it comes from using x.association :user in the factory. There are a lot of these in the various factories for this application because I’m keeping track of who is creating various items.

What I really want to say in most of these places isn’t “I need a new user that relates to this” but instead “I need a user, any user” So I’ve started using a construct that follows Model.first or in these places, so x.association :user becomes x.user { User.first or Factory(:user) }.

I went to building exactly one User and Address for the whole test suite, and reduced the suite run time from 5m13s to 1m45s by just switching to this wherever I needed an object and not a new one. I’d suggest it to anyone who is having a lot of slow tests and is using factories, it’s saved me at least a couple hours by now considering how often I run tests.