cql-pytest: add more JSON tests
cql-pytest: add more JSON tests

This patch adds several more tests reproducing bugs in toJson() and
SELECT JSON.

First add two xfailing tests reproducing two toJson() issues - #7988
and #8002. The first is that toJson() incorrectly formats values of the
"time" type - it should be a string but Scylla forgets the quotes.
The second is that toJson() format "decimal" values as JSON numbers
without using an exponent, resulting in memory allocation failure
for numbers with high exponents, like 1e1000000000.

The actual test for 1e1000000000 has to be skipped because in
debug build mode we get a crash trying this huge allocation.
So instead, we check 1e1000 - this generates a string of 1000
characters, which is much too much (should just be "1e1000")
but doesn't crash.

Then we add a reproducing test for issue #8077: When using SELECT JSON
on a function, such as count(*), ttl(v) or intAsBlob(v), Cassandra has
a specific way how it formats the result in JSON, and Scylla should do
it the same way unless we have a good reason not to.

As usual, the new tests passes on Cassandra, fails on Scylla, so is marked
xfail.

Refs #7988
Refs #8002
Refs #8077.

Signed-off-by: Nadav Har'El <625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>
Message-Id: <20210214210727.1098388-1-625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla