This patch contains 27 functional tests (in the test/cqlpy framework)
for the new CQL per-row TTL feature. The tests cover the TTL column
configuration statements (CREATE TABLE, ALTER TABLE) as well as the
actual item expiration or non-expiration depending on the value of
the expiration-time column - and also CDC events generated on expiration
and the metrics generated by the expiration process.
These tests were written together with the code, as in "test-driven
development", so they aim to cover every corner case considered during
the development, and they reproduce every bug and misstep seen during
the development process. As a result, they hopefully achieve very high
code coverage - but since we don't have a working code-coverage tool,
I can't report any specific code coverage numbers.
These tests check everything which we can check on single-node cluster.
The next patch will add additional multi-node tests for things we can't
check here with a single node - such as the scheduling group used by the
distributed work, the effect of dead nodes on the TTL functionality, and
the process of rolling upgrade.
The tests in this patch do NOT try to stress the background expiration
scanning threads, or to check how they handle topology changes, large
amounts of data or clusters spanning multiple DCs. These tests also don't
test the performance impact of these scanning threads. Because the
expiration scanning thread is identical to the one already used by
Alternator TTL, we assume that many of these aspects were already tested
for Alternator TTL and did not change when the same implementation is
used for the new CQL feature.
All new tests pass on ScyllaDB. Because the per-row TTL feature is
a new ScyllaDB feature that does not exist on Cassandra, all these
tests are skipped on Cassandra.
Because some of these tests involve waiting for expiration, they can't
be very quick. Still, because we set alternator_ttl_period_in_seconds
to 0.5 seconds in the test framework, all 27 tests running sequentially
finish in roughly 6 seconds total, which we consider acceptable.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
