[WIP][SQL][TESTS] Disable stable column aliases in tests if assumed

[MaxGekk]

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[cloud-fan]

can we change the test query to add explicit alias?

[MaxGekk]

Yep, this could be another way, but this require much more work. I will try my best, and change some test in this way.

[cloud-fan]

I think it's better to randomly switch this conf here and there. We just need to publish a good habit for writing tests: alias the expressions when necessary to have stable alias.

[MaxGekk]

I think it's better to randomly switch this conf here and there.

It is good idea, but before implementing this we should make sure that existing tests are reliable to such behaviour otherwise we will destabilize the existing CI.

We just need to publish a good habit for writing tests

Habits is nice, and I believe if a test writer assumes some naming convention, this assumption should be explicit via a config set otherwise he/she should assign an alias. How about to put this statement to the coding style?

alias the expressions when necessary to have stable alias.

I will do when it is obvious, but some tests are depend SQLConf.STABLE_DERIVED_COLUMN_ALIAS_ENABLED for unknown reasons at least for me (I cannot say why without investigation). For instance, the simple case where names should be the same in plan and in the query independently from the config:

  test("SPARK-42552: select and union without parentheses") {
    val plan = Distinct(OneRowRelation().select(Literal(1))
      .union(OneRowRelation().select(Literal(1))))
    assertEqual("select 1 union select 1", plan)
  }

fails with:

== FAIL: Plans do not match ===
 'Distinct                             'Distinct
 +- 'Union false, false                +- 'Union false, false
    :- 'Project [unresolvedalias(1)]      :- 'Project [unresolvedalias(1)]
    :  +- OneRowRelation                  :  +- OneRowRelation
    +- 'Project [unresolvedalias(1)]      +- 'Project [unresolvedalias(1)]
       +- OneRowRelation                     +- OneRowRelation