More flexible validation in `sqllogictest`

[2010YOUY01]

Is your feature request related to a problem or challenge?

When I am writing tests in #17319 :

In this test, it's intended to do a property check that the output includes 'HashJoinExec`. If such 'contains' check rule can be supported, such tests can be easier to maintain -- If the entire query plan is changed due to other modifications, we don't have to read the diff to verify if the change in this test case makes sense.

# Test that IS NOT DISTINCT FROM join produces HashJoin when used alone
query TT
EXPLAIN SELECT t1.id AS t1_id, t2.id AS t2_id, t1.val, t2.val
FROM t1
JOIN t2 ON t1.val IS NOT DISTINCT FROM t2.val
----
logical_plan
01)Projection: t1.id AS t1_id, t2.id AS t2_id, t1.val, t2.val
02)--Inner Join: t1.val = t2.val
03)----TableScan: t1 projection=[id, val]
04)----TableScan: t2 projection=[id, val]
physical_plan
01)ProjectionExec: expr=[id@0 as t1_id, id@2 as t2_id, val@1 as val, val@3 as val]
02)--CoalesceBatchesExec: target_batch_size=8192
03)----HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(val@1, val@1)]
04)------DataSourceExec: partitions=1, partition_sizes=[1]
05)------DataSourceExec: partitions=1, partition_sizes=[1]

It can look like

# Test that IS NOT DISTINCT FROM join produces HashJoin when used alone
query TT
expect contains "HashJoinExec"                        <-- Here
EXPLAIN SELECT t1.id AS t1_id, t2.id AS t2_id, t1.val, t2.val
FROM t1
JOIN t2 ON t1.val IS NOT DISTINCT FROM t2.val
----

Describe the solution you'd like

No response

• feat(small): Support <slt:ignore> marker in sqllogictest for non-deterministic expected parts #18857
• Support 'contains' check
• Support 'regex' check

Describe alternatives you've considered

No response

Additional context

I don't know if sqllogictest already support a similar extension API for custom validations, if not this issue should be promoted to the upstream.

[alan910127]

sqllogictest supports <slt:ignore> in the default validator to skip parts of a line, but that doesn’t cover this scenario. Maybe we could add something like <slt:contain> in our custom validators (sqlite_value_validator and df_value_validator):

# Test that IS NOT DISTINCT FROM join produces HashJoin when used alone
query TT
EXPLAIN SELECT t1.id AS t1_id, t2.id AS t2_id, t1.val, t2.val
FROM t1
JOIN t2 ON t1.val IS NOT DISTINCT FROM t2.val
----
<slt:contain>HashJoinExec

Not sure if this is a good solution though.

[Omega359]

Without pushing a PR to the sqllogictest-rs project I think @alan910127's idea is about the best that we can do.