cql-pytest: add tests for non-support of unicode equivalence`
cql-pytest: add tests for non-support of unicode equivalence`

In issue #7843 there were questions raised on how much does Scylla
support the notion of Unicode Equivalence, a.k.a. Unicode normalization.

Consider the Spanish letter ñ - it can be represented by a single Unicode
character 00F1, but can also be represented as a 006E (lowercase "n")
followed by a 0303 ("combining tilde"). Unicode specifies that these
two representations should be considered "equivalent" for purposes of
sorting or searching. But the following tests demonstrates that this
is not, in fact, supported in Scylla or Cassandra:

1. If you use one representation as the key, then looking up the other one
   will not find the row. Scylla (and Cassandra) do *not* consider
   the two strings equivalent.

2. The LIKE operator (a Scylla-only extension) doesn't know that
   the single-character ñ begins with an n, or that the two-character
   ñ is just a single character.
   This is despite the thinking on #7843 which by using ICU in the
   implementation of LIKE, we somehow got support for this. We didn't.

Refs #7843

Signed-off-by: Nadav Har'El <625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>
Message-Id: <20201229125330.3401954-1-625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>

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