Are all exceptions supressed in Rail integration tests?

I've recently spotted a missing I18n translation in a Rails project, but I have enabled exceptions in the test environment so I would have expected to have found it during testing. It seems that integration tests happily ignore exceptions, or perhaps I18n has chosen not to throw one.

Is this just the way Rails works or is there some magic flag that I've somehow enabled? I can create a unit test to repro the issue but since I already have an integration test that hits exactly the right code, it would be nice if I could use that.