I have the following method using upsert:
def job_code
@code = JobCode.new(params[:api])
selector = {:store_id => @code.store_id, :source_id => @code.source_id}
setter = { :name => @code.name, :created_at => Time.now, :updated_at => Time.now }
JobCode.upsert(selector, setter)
render_json(@code, :created)
end

And here is the spec that is giving me trouble:
describe 'job_code' do
context 'when it is a new job_code' do
Given(:params) { {:format => 'json', :api=>{ :store_id=> 1, :source_id=>25, :name=>'Server'}} }
Then { lambda{ post :job_code, params }.should change(JobCode, :count) }
end

context 'when the item already exists' do
  Given!(:code) { FactoryGirl.create :job_code }
  Given(:params) {  {:format => 'json', :api=>{ :store_id=> code.store_id, :source_id=>code.source_id, :name=>code.name}} }
  Then { lambda{ post :job_code, params }.should_not change(JobCode, :count) }   
end

end

I can run each of these specs individually and everything works well, but when I run them together, I get the following error:

1. ApiController job_code when the item already exists
   Failure/Error: Then { lambda{ post :job_code, params }.should_not change(JobCode, :count) }
   PG::Error:
   ERROR: current transaction is aborted, commands ignored until end of transaction block

I can call this method with a script many times back-to back, and it works well. I'm also using upsert elsewhere without an issue. Also, all rows are successfully loaded in the database in all cases except for the test. Not sure if this is an Upsert issue or user error, but any insight is much appreciated!