Fix issue where case expression is evaluated too early

[PavelSafronov]

Fix issue where case expression is evaluated and the result is being treated as a literal.

Fixes dolthub/dolt#4716

[max-hoffman]

LGTM, it is usually simpler to avoid new test setup harnesses when we can avoid it, but we don't appear to have any enginetests that touch enums? Which seems kind of concerning.

[fulghum]

Looks good! Nice work with this fix. ⚡

Max had a good comment about spinning up a new enginetest Test method... okay with me, but you should also add that to dolt, so that dolt_engine_test runs that new Test method. Alternatively... it might be a little simpler to just put this test in the (unorganized grab bag) queries.ScriptTests. Either way works for me.

[PavelSafronov]

Thanks for the review, @max-hoffman and @fulghum!

we don't appear to have any enginetests that touch enums? Which seems kind of concerning.

Looks like we have enum tests in sql/enumtype_test.go, but yeah, there's a lack of table enum tests.

Alternatively... it might be a little simpler to just put this test in the (unorganized grab bag) queries.ScriptTests.

That seems like a good place, I'll move the new tests to that location.

I found the setup_data.sg.go changes to be strange and honestly, I don't get them. What is the benefit of translating plain files of SQL (no intellisense, no type checking, etc.) into go files?

[max-hoffman]

I found the setup_data.sg.go changes to be strange and honestly, I don't get them. What is the benefit of translating plain files of SQL (no intellisense, no type checking, etc.) into go files?

There might not be a good one! The current structure is the result of rewriting the previous format, which used the database, table, and schema APIs in Go to setup tests. The current format uses SQL queries to do setup, which I think is a comparative improvement. The duplication provides an IR that we can easily inline in code; passing around batched blocks SQL strings for custom bootstrapping was seen as undesirable at the time. Alternative IRs with less duplication might look like at Aaron's server-driver yaml, the correctness test format, and cockroach's test format. Note that all of these require investments in testing infrastructure.