gistfile1.rb

# So Tags has many "Freetaggables", a polymorphic association. Contacts is one of those freetaggables.

# My mentor was working on some old imports and this bug crops up.

# The code below raises an error. The record is invalid for some reason.

# Turns out since the join has a composite key it is failing - it isn't unique. That doesn't seem possible.

# It just so happens there is a really subtle bug where if you don't save both models before associating them you get a duplicate record in the join

it "should not create duplicate taggings" do
  t = Tag.create(:title => 'auto tag')
  c = Contact.new
  c.tags << t
  lambda { c.save }.should_not raise_error 

  #EHH, wrong. Raises error "#<ActiveRecord::RecordInvalid: Validation failed: Freetaggable type has already been taken>"
  # Sooooo descriptive

end

# Add the appropriate save and we no longer have a problem

it "should not create duplicate taggings" do
  t = Tag.create(:title => 'auto tag') # create implies a save here
  c = Contact.new
  c.save
  c.tags << t
  lambda { c.save }.should_not raise_error 
end

# I only found this out from a rails lighthouse ticket 
# https://rails.lighthouseapp.com/projects/8994/tickets/177-regression-of-ticket-2888-habtm-inserts-duplicate-rows-into-join-table
# that implied to me the expect action of the developer is too save both models beforehand. Doing so works - it would be nice, however, if the association adding (#<<) would let me know I hadn't saved though.