[EPAC-1873]: add integration tests for /api/v1/on-this-day handler

[riddim-developer-bot]

Why

The on-this-day handler's date-arithmetic SQL (month/day extraction, leap-year Feb 29, strict < boundary) is untestable by the existing unit suite — all 6 unit tests use fake row scanners with no real Postgres. Any off-by-one in the SQL ships silently. This PR adds the DB-backed integration test layer to catch those regressions.

What changed

• New file: backend/on-this-day/main_integration_test.go (280 lines, //go:build integration)
  • Six named tests, each seeding speeches rows and calling queryOnThisDay directly (bypassing the package-level dbConn) or HandleRequest for HTTP-layer assertions
  • Uses _testdb.Connect(t) and _testdb.SeedSpeech from the EPAC-1869 harness; isolation via DELETE FROM speeches before each test
  • TestOnThisDayLeapYearFeb29 documents that Go's time.Parse("2006-01-02", "2023-02-29") returns "day out of range", so the handler returns HTTP 400 for non-leap Feb 29

Trade-offs not taken

• WithTx for isolation: Using BEGIN/ROLLBACK would hide seeded rows from the handler's own DB connection (which connects separately via DATABASE_URL). The DELETE FROM speeches approach matches the search integration test pattern and keeps both connections seeing the same state.
• Calling HandleRequest for all tests: The handler's getDBConn uses a package-level *pgx.Conn. Calling queryOnThisDay directly with the test connection avoids polluting or depending on that global and matches the search integration test approach.

Test plan

Run the full integration suite locally with Docker (when available):

docker compose -f docker-compose.test.yml up -d
DATABASE_URL=postgresql://epac:epac@localhost:5432/epac_test \
  go test -tags=integration -v ./... 2>&1 | grep -E "^(=== RUN|--- PASS|--- FAIL|FAIL|ok)"

Expected: all 6 named tests pass. Unit tests unaffected (go test ./... in backend/on-this-day passes without DATABASE_URL).

Verification evidence

• go build ./... from backend/on-this-day/: PASS (no output)
• go vet -tags=integration ./... from backend/on-this-day/: PASS (no output)
• go test ./... (unit tests, no DB): PASS — ok epac/on-this-day 0.384s
• Integration tests: SKIPPED locally — Docker daemon not running. CI runs them via services: postgres:16 sidecar in backend-tests.yml.

Resolves EPAC-1873

Reviewer-Boundary: review-only

[riddim-reviewer-bot]

⚠️ Autonomous review liveness watchdog

Symphony expected a reviewer-bot review for the current autonomous PR head within the configured SLA window, but none was found.

• PR: [EPAC-1873]: add integration tests for /api/v1/on-this-day handler #457
• Repo: RiddimSoftware/epac
• Head SHA: 5fddf40456944f08c85a2ce0c8abb6c5d6c9e569
• Suspected missing reviewer owner: RiddimSoftware/epac
• Review SLA window: 300000 ms
• PR last activity: 2026-05-14T23:01:29Z
• Last heartbeat: fresh at 2026-05-14T23:12:38Z from riddim1.local @ e21a1a029dccc09640758c5b4e1c9a61c2e3ede0

[riddim-reviewer-bot]

ReviewAutonomousPR

• Verdict: approve
• Reviewer boundary: review_only
• Acceptance criteria coverage: covered=5, missing=0, unclear=1

Summary

The PR adds the requested integration coverage for /api/v1/on-this-day and keeps the existing unit behavior unchanged; no required correctness defects are present in the changes.

Actionable findings

1. nit / follow_up — Timezone boundary test does not enforce a non-UTC runtime context (backend/on-this-day/main_integration_test.go)
   • The timezone test validates DATE-only behavior by calling queryOnThisDay directly, but it does not shift process timezone or invoke the handler path while forcing a UTC-offset context. This means subtle request-parsing or request-to-DB timezone regressions tied specifically to handler/runtime timezone handling are not exercised in this test.
   • Actionability: follow_up

Acceptance criteria coverage

• covered — TestOnThisDayHappyPath_ReturnsMatchingSittings seeds 3 speeches on 2010-03-15, 2 on 2015-03-15, extra-date rows, queries 2026-03-15, asserts only March-15 records
  • Implemented in TestOnThisDayHappyPath_ReturnsMatchingSittings with DB seeding and queryOnThisDay assertions.
  • Actionability: none
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayHappyPath_ReturnsMatchingSittings
• covered — TestOnThisDayLeapYearFeb29 asserts 2020-02-29 matches 2024-02-29 and documents invalid 2023-02-29 handling
  • Test seeds 2020 leap-day rows, verifies 2024 query returns them, and checks 2023-02-29 returns HTTP 400.
  • Actionability: none
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayLeapYearFeb29
• covered — TestOnThisDayNoMatchingDate_ReturnsEmptyShape returns 200 with items:[] and date echo for no matches
  • Direct DB query and handler response assertions both verify empty shape and non-nil items array with echoed date.
  • Actionability: none
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayNoMatchingDate_ReturnsEmptyShape
• covered — TestOnThisDayLimitBound validates limit=1 and clamp behavior for limit=999
  • Validates direct limit=1 result count and verifies parseLimit(999) equals maxLimit, then queries with maxLimit.
  • Actionability: none
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayLimitBound
• covered — TestOnThisDayInvalidDateFormat_Returns400 checks malformed date format maps to HTTP 400 with error field
  • Table-driven cases validate 400 and non-empty error field.
  • Actionability: none
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayInvalidDateFormat_Returns400
• unclear — TestOnThisDayTimezoneBoundary seeds DATE value and verifies query for matching calendar date under shifted timezone context
  • Test validates calendar-date behavior but does not explicitly set/process timezone-shifted context or go through handler path for this scenario.
  • Actionability: follow_up
  • Evidence: backend/on-this-day/main_integration_test.go: TestOnThisDayTimezoneBoundary
  • Suggested follow-up: Add timezone-offset context assertion around handler call