sql: parse EXECUTE UNIT TEST

[sjwiesman]

Summary

Adds parser support for EXECUTE UNIT TEST, a SQL-level construct for
declarative unit testing of views and materialized views. The plan side returns
unsupported.

Syntax

 EXECUTE UNIT TEST <test_name>
      FOR <target_name>
      [AT TIME <expr>]
      [MOCK <mock_name> ( <col_def> [, ...] ) AS ( <query> ) ,]...
      EXPECTED ( <col_def> [, ...] ) AS ( <query> )

• <test_name> — identifier, reported in test output.
• FOR <view> — fully-qualified name of the view or materialized view
  under test.
• AT TIME <expr> (optional) — time at which to evaluate the view, for
  testing temporal logic.
• MOCK <input_view> (cols) AS <query> (zero or more) — substitutes
  <input_view> with the rows produced by <query> for the duration of
  this test. Column list defines the schema the test expects from the
  mocked input.
• EXPECTED (cols) AS <query> (required, exactly one) — the rows the
  view under test must produce.

Example

  EXECUTE UNIT TEST t FOR v
      MOCK a(x int) AS (SELECT 1),
      MOCK b(y int) AS (SELECT 2)
      EXPECTED (z int) AS (SELECT 3);

Scope

• New keywords: UNIT, TEST, MOCK, EXPECTED (src/sql-lexer).
• New AST nodes: ExecuteUnitTestStatement, MockViewDef,
  ExpectedResultDef (src/sql-parser/ast/defs/statement.rs).
• Parser entry from EXECUTE UNIT TEST ... (src/sql-parser/parser.rs).
• Plan side returns unsupported — execution is intentionally out of
  scope for this PR.

🤖 Generated with Claude Code

[sjwiesman]

Purposefully left this undocumented because you can't actually run it.

[def-]

MOCK and EXPECTED need to be added in is_reserved_in_column_alias or is_reserved_in_table_alias

Multiple MOCK ..., MOCK... don't parse:

ERR: Expected left parenthesis, found MOCK

[def-]

Suggested change

	f.write_str(" EXPECTED");
	f.write_str(" EXPECTED ");

[sjwiesman]

Thanks for the review. I realized the grammar was not as restrictive as I intended. Made a slightly different change but should still handle your case.

[ggevay]

Requiring the parens was a good idea to avoid adding stuff to is_reserved_in_column_alias/is_reserved_in_table_alias!

Looks good to me now, only some minor things:

• Might be a bit surprising that a comma is needed even after the final MOCK, i.e., before the EXPECTED.
• You could add a few more tests. (also negative ones)

[sjwiesman]

Happy to make both updates before merging!

[ggevay]

Thanks, looks great to me!

@def-, it seems my approval is not overriding your "Changes requested" review, so I think you need to drop it (if you agree with the fix).

[def-]

The PR author can dismiss a review with a reason I think.

[sjwiesman]

@def- TIL!