assert_difference has morphed
This is just a little note that assert_difference, the ultimate test helper, has been merged into core. The only issue is that it has changed a bit from the version that I have used. I always used something along the lines of:
assert_difference Post, :count do Post.create_valid end
The version that got merged into core instead accepts a string like so:
assert_difference 'Post.count' do Post.create_valid end
Not sure why the syntax is different but that is neither here nor there for me. The only down side is I had to go through all my tests and fix the incorrect arguments. Just thought I would say something here so others know what is going wrong when all their tests fail after upgrading to edge.