Better feedback when a cassette doesn't match

[soffes]

If you specify a cassette, it exists, and doesn't contain the request you specified, it would be really helpful if it said why it thinks the request you specified doesn't match the one in the cassette.

[soffes]

In this case, I had added the cassette to the framework instead of the test target by mistake. It would be super cool if we could detect that.

[kiliankoe]

I realize this issue is rather old, but I'm running into something nonetheless and would love to know why it fails. All I'm seeing is the following, but only on Travis CI 😕 Everything works just fine locally.

❌  fatal error: [DVR] Invalid request. The request was not found in the cassette.: file /Users/travis/build/kiliankoe/DVB/Carthage/Checkouts/DVR/DVR/SessionDataTask.swift, line 55

Unfortunately I'm not even entirely sure which request lookup fails 🙈 I'm seeing timeouts on a subset of all tests using VCR.