I'm starting the process of vetting our software with MongoDB 1.8. I had been running MongoDB 1.6.0 on my Mac (which we also currently run in production). Today I installed MongoDB 1.8.0 and pointed it at the data files that had been created with 1.6.0. All of my tests passed and everything seemed fine.

Then I enabled journaling (--journal). Once I did this, one of my tests started failing with this message:

Failures:
1) SaveWave::Model::MongoDB::Upc should create
Failure/Error: @upc = Factory.create(:upc)
: _a != -1

1. ./spec/integration/mongodb/upc_spec.rb:13:in `block (2 levels) in <top (required)>'

2) SaveWave::Model::MongoDB::Upc should update
Failure/Error: @upc = Factory.create(:upc)
: _a != -1

1. ./spec/integration/mongodb/upc_spec.rb:13:in `block (2 levels) in <top (required)>'

3) SaveWave::Model::MongoDB::Upc should destroy
Failure/Error: @upc = Factory.create(:upc)
: _a != -1

1. ./spec/integration/mongodb/upc_spec.rb:13:in `block (2 levels) in <top (required)>'

When I turn off journaling, the test passes. Line 13 of the test where it keeps failing is:

before :each do
@upc = Factory.create(:upc) # <-- Line 13
end

And the relevant FactoryGirl definition is:

Factory.define :upc, :class => SaveWave::Model::MongoDB::Upc do |upc|
upc.name "Coca Cola"
upc.active true
upc.start_date DateTime.civil(2010, 10, 1, 0, 0, 0)
upc.end_date DateTime.civil(2011, 9, 30, 11, 59, 59)
upc.identifier "8395837859183"
upc.excluded_states ["MA", "OR"]
end

Nothing obvious pops out here. Let me know if there's any more info I can provide to help debug this.