Many tests verify exception messages. Currently, they do so via
verbose lambdas or inner functions that hide test-failure locations.
This patch adds utilities for quick creation of message-checking tests
and replaces existing ad-hoc methods with these new utilities.
Tests: unit (dev)
Signed-off-by: Dejan Mircevski <dejan@scylladb.com>
Message-Id: <20190506210006.124645-1-dejan@scylladb.com>
