#1 Validate Error Message for Failed Tests

[Gavin Kingsley]

At the moment, when a test fails logging must be used
to validate that it fails for the correct reason. If the
schema is changed there is no automatic guarantee that
it still fails for the correct reason.

The easiest validation is to ensure that the error
message contains the test "desc" text.

This should probably be controlled by an option for
backwards compatibility.