Followup #4 from the SP37 final-state tracker. The previous
BACKFILL_SQL constant in test_migration_0020.py was a hand-copied
duplicate of the migration's UPDATE statement. A future contributor
could edit one without the other and the test would silently
replay a different SQL than production — defeating the regression.
Fix: tests now load the migration file at test time and extract
its UPDATE via the same splitter db_migrate.run() uses (strip
'--' comments, split on ';'). The test can never disagree with
what production runs.
Changes:
* test_migration_0020.py:
- Remove the hand-copied BACKFILL_SQL constant
- Add _migration_0020_path(), _extract_update_statements(),
and _load_migration_0020_backfill_sql() helpers
- Replace 3 BACKFILL_SQL references with helper calls
* test_migration_0020_no_drift.py (new, 3 tests):
- test_migration_0020_backfill_sql_uses_migration_file
(asserts the extracted SQL targets the right column + path)
- test_migration_0020_backfill_sql_is_non_empty_single_statement
- test_migration_0020_has_exactly_one_update (guardrail against
future contributors adding a second UPDATE — the extraction
fails loudly so the test author can decide which is the
backfill)
Tests: 43/43 pass in 1.46s (full SP37 followup chain).
Imports across test files match the existing pattern (test_store.py
imports from test_store_reconcile.py).
Nora