Approver should not report a passing test if it generated the .approved file

[npryce]

If working incrementally, I'll start with an almost empty implementation. E.g. it'll return an empty string or somesuch. I'll run the test to see a failure.

The Approver generates an empty approved file if one doesn't exist. It then compares this to the output from the code. They are the same because I've only just started writing the code. And so the Approver reports a test pass.

It should report a test failure, since I've not actually approved any output yet.